diff --git a/Cargo.lock b/Cargo.lock
index 3953727c76..651c6cb421 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2743,6 +2743,8 @@ dependencies = [
  "num-format",
  "serde",
  "serde_json",
+ "strum 0.24.1",
+ "strum_macros 0.24.3",
  "sys-locale",
  "thiserror",
  "typetag",
diff --git a/crates/nu-command/src/bits/and.rs b/crates/nu-command/src/bits/and.rs
index f7e3a995c6..920e3d19a4 100644
--- a/crates/nu-command/src/bits/and.rs
+++ b/crates/nu-command/src/bits/and.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits and")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .required(
                 "target",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/bits/not.rs b/crates/nu-command/src/bits/not.rs
index a6baa27e68..885c887bc5 100644
--- a/crates/nu-command/src/bits/not.rs
+++ b/crates/nu-command/src/bits/not.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits not")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .switch(
                 "signed",
                 "always treat input number as a signed number",
diff --git a/crates/nu-command/src/bits/or.rs b/crates/nu-command/src/bits/or.rs
index 5c551bf185..9c84c84d9b 100644
--- a/crates/nu-command/src/bits/or.rs
+++ b/crates/nu-command/src/bits/or.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits or")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .required(
                 "target",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/bits/rotate_left.rs b/crates/nu-command/src/bits/rotate_left.rs
index f7a11522e1..05163cdce7 100644
--- a/crates/nu-command/src/bits/rotate_left.rs
+++ b/crates/nu-command/src/bits/rotate_left.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 use num_traits::int::PrimInt;
 use std::fmt::Display;
@@ -18,6 +18,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits rol")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .required("bits", SyntaxShape::Int, "number of bits to rotate left")
             .switch(
                 "signed",
diff --git a/crates/nu-command/src/bits/rotate_right.rs b/crates/nu-command/src/bits/rotate_right.rs
index 2b5c62fb37..d141f34f66 100644
--- a/crates/nu-command/src/bits/rotate_right.rs
+++ b/crates/nu-command/src/bits/rotate_right.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 use num_traits::int::PrimInt;
 use std::fmt::Display;
@@ -18,6 +18,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits ror")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .required("bits", SyntaxShape::Int, "number of bits to rotate right")
             .switch(
                 "signed",
diff --git a/crates/nu-command/src/bits/shift_left.rs b/crates/nu-command/src/bits/shift_left.rs
index 62c982a872..3c7696235c 100644
--- a/crates/nu-command/src/bits/shift_left.rs
+++ b/crates/nu-command/src/bits/shift_left.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 use num_traits::CheckedShl;
 use std::fmt::Display;
@@ -18,6 +18,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits shl")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .required("bits", SyntaxShape::Int, "number of bits to shift left")
             .switch(
                 "signed",
diff --git a/crates/nu-command/src/bits/shift_right.rs b/crates/nu-command/src/bits/shift_right.rs
index 1ffde30a8d..fc1cde9081 100644
--- a/crates/nu-command/src/bits/shift_right.rs
+++ b/crates/nu-command/src/bits/shift_right.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 use num_traits::CheckedShr;
 use std::fmt::Display;
@@ -18,6 +18,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits shr")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .required("bits", SyntaxShape::Int, "number of bits to shift right")
             .switch(
                 "signed",
diff --git a/crates/nu-command/src/bits/xor.rs b/crates/nu-command/src/bits/xor.rs
index 394ea8a3b5..a38cdb9390 100644
--- a/crates/nu-command/src/bits/xor.rs
+++ b/crates/nu-command/src/bits/xor.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("bits xor")
+            .input_output_types(vec![(Type::Int, Type::Int)])
+            .vectorizes_over_list(true)
             .required(
                 "target",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/bytes/add.rs b/crates/nu-command/src/bytes/add.rs
index de6f5521bd..e7e12d7a5d 100644
--- a/crates/nu-command/src/bytes/add.rs
+++ b/crates/nu-command/src/bytes/add.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     added_data: Vec<u8>,
@@ -30,6 +30,8 @@ impl Command for BytesAdd {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes add")
+            .input_output_types(vec![(Type::Binary, Type::Binary)])
+            .vectorizes_over_list(true)
             .required("data", SyntaxShape::Binary, "the binary to add")
             .named(
                 "index",
diff --git a/crates/nu-command/src/bytes/at.rs b/crates/nu-command/src/bytes/at.rs
index c86eccc67b..53b4534167 100644
--- a/crates/nu-command/src/bytes/at.rs
+++ b/crates/nu-command/src/bytes/at.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 use std::cmp::Ordering;
 
@@ -115,6 +115,8 @@ impl Command for BytesAt {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes at")
+            .input_output_types(vec![(Type::Binary, Type::Binary)])
+            .vectorizes_over_list(true)
             .required("range", SyntaxShape::Any, "the indexes to get bytes")
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/bytes/build_.rs b/crates/nu-command/src/bytes/build_.rs
index 4b4f0b6239..e4ab0247f7 100644
--- a/crates/nu-command/src/bytes/build_.rs
+++ b/crates/nu-command/src/bytes/build_.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -24,6 +24,7 @@ impl Command for BytesBuild {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("bytes build")
+            .input_output_types(vec![(Type::Nothing, Type::Binary)])
             .rest("rest", SyntaxShape::Any, "list of bytes")
             .category(Category::Bytes)
     }
diff --git a/crates/nu-command/src/bytes/collect.rs b/crates/nu-command/src/bytes/collect.rs
index 34ddc44707..92173fe4c7 100644
--- a/crates/nu-command/src/bytes/collect.rs
+++ b/crates/nu-command/src/bytes/collect.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone, Copy)]
@@ -16,6 +16,7 @@ impl Command for BytesCollect {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes collect")
+            .input_output_types(vec![(Type::List(Box::new(Type::Binary)), Type::Binary)])
             .optional(
                 "separator",
                 SyntaxShape::Binary,
diff --git a/crates/nu-command/src/bytes/ends_with.rs b/crates/nu-command/src/bytes/ends_with.rs
index 69416f19be..0b41d2e626 100644
--- a/crates/nu-command/src/bytes/ends_with.rs
+++ b/crates/nu-command/src/bytes/ends_with.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     pattern: Vec<u8>,
@@ -28,6 +28,7 @@ impl Command for BytesEndsWith {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes ends-with")
+            .input_output_types(vec![(Type::Binary, Type::Bool)])
             .required("pattern", SyntaxShape::Binary, "the pattern to match")
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/bytes/index_of.rs b/crates/nu-command/src/bytes/index_of.rs
index 52f3765b21..084d755c5f 100644
--- a/crates/nu-command/src/bytes/index_of.rs
+++ b/crates/nu-command/src/bytes/index_of.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::{Call, CellPath};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 struct Arguments {
@@ -29,6 +29,10 @@ impl Command for BytesIndexOf {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes index-of")
+            .input_output_types(vec![
+                (Type::Binary, Type::Int),
+                (Type::Binary, Type::List(Box::new(Type::Int))),
+            ])
             .required(
                 "pattern",
                 SyntaxShape::Binary,
diff --git a/crates/nu-command/src/bytes/length.rs b/crates/nu-command/src/bytes/length.rs
index 13f3f70af1..3823cbe3bc 100644
--- a/crates/nu-command/src/bytes/length.rs
+++ b/crates/nu-command/src/bytes/length.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct BytesLen;
@@ -16,6 +16,8 @@ impl Command for BytesLen {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes length")
+            .input_output_types(vec![(Type::Binary, Type::Int)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/bytes/remove.rs b/crates/nu-command/src/bytes/remove.rs
index 42807c6d53..e9106615ed 100644
--- a/crates/nu-command/src/bytes/remove.rs
+++ b/crates/nu-command/src/bytes/remove.rs
@@ -3,7 +3,8 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
+    Value,
 };
 
 struct Arguments {
@@ -29,6 +30,7 @@ impl Command for BytesRemove {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes remove")
+            .input_output_types(vec![(Type::Binary, Type::Binary)])
             .required("pattern", SyntaxShape::Binary, "the pattern to find")
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/bytes/replace.rs b/crates/nu-command/src/bytes/replace.rs
index c2d8bffb1a..124d018b4e 100644
--- a/crates/nu-command/src/bytes/replace.rs
+++ b/crates/nu-command/src/bytes/replace.rs
@@ -3,7 +3,8 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
+    Value,
 };
 
 struct Arguments {
@@ -29,6 +30,7 @@ impl Command for BytesReplace {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes replace")
+            .input_output_types(vec![(Type::Binary, Type::Binary)])
             .required("find", SyntaxShape::Binary, "the pattern to find")
             .required("replace", SyntaxShape::Binary, "the replacement pattern")
             .rest(
diff --git a/crates/nu-command/src/bytes/reverse.rs b/crates/nu-command/src/bytes/reverse.rs
index 1ddd583f3c..54b945d6ff 100644
--- a/crates/nu-command/src/bytes/reverse.rs
+++ b/crates/nu-command/src/bytes/reverse.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 
@@ -17,6 +17,7 @@ impl Command for BytesReverse {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes reverse")
+            .input_output_types(vec![(Type::Binary, Type::Binary)])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/bytes/starts_with.rs b/crates/nu-command/src/bytes/starts_with.rs
index 503e4ca06e..4242c22f7c 100644
--- a/crates/nu-command/src/bytes/starts_with.rs
+++ b/crates/nu-command/src/bytes/starts_with.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     pattern: Vec<u8>,
@@ -28,6 +28,7 @@ impl Command for BytesStartsWith {
 
     fn signature(&self) -> Signature {
         Signature::build("bytes starts-with")
+            .input_output_types(vec![(Type::Binary, Type::Bool)])
             .required("pattern", SyntaxShape::Binary, "the pattern to match")
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/charting/hashable_value.rs b/crates/nu-command/src/charting/hashable_value.rs
index 2a99b2f69f..69e68ac351 100644
--- a/crates/nu-command/src/charting/hashable_value.rs
+++ b/crates/nu-command/src/charting/hashable_value.rs
@@ -13,7 +13,7 @@ use std::hash::{Hash, Hasher};
 /// ```text
 /// assert_eq!(HashableValue::Bool {val: true, span: Span{start: 0, end: 1}}, HashableValue::Bool {val: true, span: Span{start: 90, end: 1000}})
 /// ```
-#[derive(Eq, Debug)]
+#[derive(Eq, Debug, Ord, PartialOrd)]
 pub enum HashableValue {
     Bool {
         val: bool,
diff --git a/crates/nu-command/src/charting/histogram.rs b/crates/nu-command/src/charting/histogram.rs
index eba15dae1f..88832da9e6 100644
--- a/crates/nu-command/src/charting/histogram.rs
+++ b/crates/nu-command/src/charting/histogram.rs
@@ -1,10 +1,11 @@
 use super::hashable_value::HashableValue;
+use itertools::Itertools;
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape,
-    Value,
+    Type, Value,
 };
 use std::collections::HashMap;
 use std::iter;
@@ -24,6 +25,7 @@ impl Command for Histogram {
 
     fn signature(&self) -> Signature {
         Signature::build("histogram")
+            .input_output_types(vec![(Type::List(Box::new(Type::Any)), Type::Table(vec![])),])
             .optional("column-name", SyntaxShape::String, "column name to calc frequency, no need to provide if input is just a list")
             .optional("frequency-column-name", SyntaxShape::String, "histogram's frequency column, default to be frequency column output")
             .named("percentage-type", SyntaxShape::String, "percentage calculate method, can be 'normalize' or 'relative', in 'normalize', defaults to be 'normalize'", Some('t'))
@@ -36,23 +38,48 @@ impl Command for Histogram {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Get a histogram for the types of files",
+                description: "Compute a histogram of file types",
                 example: "ls | histogram type",
                 result: None,
             },
             Example {
                 description:
-                    "Get a histogram for the types of files, with frequency column named freq",
+                    "Compute a histogram for the types of files, with frequency column named freq",
                 example: "ls | histogram type freq",
                 result: None,
             },
             Example {
-                description: "Get a histogram for a list of numbers",
-                example: "echo [1 2 3 1 1 1 2 2 1 1] | histogram",
-                result: None,
+                description: "Compute a histogram for a list of numbers",
+                example: "echo [1 2 1] | histogram",
+                result: Some(Value::List {
+                        vals: vec![Value::Record {
+                            cols: vec!["value".to_string(), "count".to_string(), "quantile".to_string(), "percentage".to_string(), "frequency".to_string()],
+                            vals: vec![
+                                Value::test_int(1),
+                                Value::test_int(2),
+                                Value::test_float(0.6666666666666666),
+                                Value::test_string("66.67%"),
+                                Value::test_string("******************************************************************"),
+                            ],
+                            span: Span::test_data(),
+                        },
+                        Value::Record {
+                            cols: vec!["value".to_string(), "count".to_string(), "quantile".to_string(), "percentage".to_string(), "frequency".to_string()],
+                            vals: vec![
+                                Value::test_int(2),
+                                Value::test_int(1),
+                                Value::test_float(0.3333333333333333),
+                                Value::test_string("33.33%"),
+                                Value::test_string("*********************************"),
+                            ],
+                            span: Span::test_data(),
+                        }],
+                        span: Span::test_data(),
+                    }
+                 ),
             },
             Example {
-                description: "Get a histogram for a list of numbers, and percentage is based on the maximum value",
+                description: "Compute a histogram for a list of numbers, and percentage is based on the maximum value",
                 example: "echo [1 2 3 1 1 1 2 2 1 1] | histogram --percentage-type relative",
                 result: None,
             }
@@ -213,7 +240,7 @@ fn histogram_impl(
         freq_column.to_string(),
     ];
     const MAX_FREQ_COUNT: f64 = 100.0;
-    for (val, count) in counter.into_iter() {
+    for (val, count) in counter.into_iter().sorted() {
         let quantile = match calc_method {
             PercentageCalcMethod::Normalize => count as f64 / total_cnt as f64,
             PercentageCalcMethod::Relative => count as f64 / max_cnt as f64,
diff --git a/crates/nu-command/src/conversions/fmt.rs b/crates/nu-command/src/conversions/fmt.rs
index f209b0a1d2..832bdd7f9c 100644
--- a/crates/nu-command/src/conversions/fmt.rs
+++ b/crates/nu-command/src/conversions/fmt.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,7 +19,9 @@ impl Command for Fmt {
     }
 
     fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("fmt").category(Category::Conversions)
+        Signature::build("fmt")
+            .input_output_types(vec![(Type::Number, Type::Record(vec![]))])
+            .category(Category::Conversions)
     }
 
     fn search_terms(&self) -> Vec<&str> {
diff --git a/crates/nu-command/src/conversions/into/binary.rs b/crates/nu-command/src/conversions/into/binary.rs
index 0b23968cf8..884d5f2211 100644
--- a/crates/nu-command/src/conversions/into/binary.rs
+++ b/crates/nu-command/src/conversions/into/binary.rs
@@ -4,7 +4,7 @@ use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,16 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("into binary")
+            .input_output_types(vec![
+                (Type::Binary, Type::Binary),
+                (Type::Int, Type::Binary),
+                (Type::Number, Type::Binary),
+                (Type::String, Type::Binary),
+                (Type::Bool, Type::Binary),
+                (Type::Filesize, Type::Binary),
+                (Type::Date, Type::Binary),
+            ])
+            .allow_variants_without_examples(true) // TODO: supply exhaustive examples
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/conversions/into/bool.rs b/crates/nu-command/src/conversions/into/bool.rs
index 97a37d2f8f..b0af12143c 100644
--- a/crates/nu-command/src/conversions/into/bool.rs
+++ b/crates/nu-command/src/conversions/into/bool.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,13 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("into bool")
+            .input_output_types(vec![
+                (Type::Int, Type::Bool),
+                (Type::Number, Type::Bool),
+                (Type::String, Type::Bool),
+                (Type::Bool, Type::Bool),
+                (Type::List(Box::new(Type::Any)), Type::Table(vec![])),
+            ])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
@@ -89,6 +96,11 @@ impl Command for SubCommand {
                 example: "1 | into bool",
                 result: Some(Value::boolean(true, span)),
             },
+            Example {
+                description: "convert decimal to boolean",
+                example: "0.3 | into bool",
+                result: Some(Value::boolean(true, span)),
+            },
             Example {
                 description: "convert decimal string to boolean",
                 example: "'0.0' | into bool",
diff --git a/crates/nu-command/src/conversions/into/datetime.rs b/crates/nu-command/src/conversions/into/datetime.rs
index daafbe9c48..9650469ee4 100644
--- a/crates/nu-command/src/conversions/into/datetime.rs
+++ b/crates/nu-command/src/conversions/into/datetime.rs
@@ -7,7 +7,7 @@ use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 struct Arguments {
@@ -64,7 +64,11 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("into datetime")
-            .named(
+        .input_output_types(vec![
+            (Type::Int, Type::Date),
+            (Type::String, Type::Date),
+        ])
+        .named(
                 "timezone",
                 SyntaxShape::String,
                 "Specify timezone if the input is a Unix timestamp. Valid options: 'UTC' ('u') or 'LOCAL' ('l')",
diff --git a/crates/nu-command/src/conversions/into/decimal.rs b/crates/nu-command/src/conversions/into/decimal.rs
index a22179ad5a..95f240f469 100644
--- a/crates/nu-command/src/conversions/into/decimal.rs
+++ b/crates/nu-command/src/conversions/into/decimal.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,11 +15,16 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("into decimal").rest(
-            "rest",
-            SyntaxShape::CellPath,
-            "optionally convert text into decimal by column paths",
-        )
+        Signature::build("into decimal")
+            .input_output_types(vec![
+                (Type::String, Type::Number),
+                (Type::Bool, Type::Number),
+            ])
+            .rest(
+                "rest",
+                SyntaxShape::CellPath,
+                "optionally convert text into decimal by column paths",
+            )
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/conversions/into/duration.rs b/crates/nu-command/src/conversions/into/duration.rs
index b6459e1466..9257d796f8 100644
--- a/crates/nu-command/src/conversions/into/duration.rs
+++ b/crates/nu-command/src/conversions/into/duration.rs
@@ -3,7 +3,7 @@ use nu_parser::parse_duration_bytes;
 use nu_protocol::{
     ast::{Call, CellPath, Expr},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Unit,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Unit,
     Value,
 };
 
@@ -17,6 +17,13 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("into duration")
+            .input_output_types(vec![
+                (Type::String, Type::Duration),
+                (Type::Duration, Type::Duration),
+                // TODO: --convert option should be implemented as `format duration`
+                (Type::String, Type::String),
+                (Type::Duration, Type::String),
+            ])
             .named(
                 "convert",
                 SyntaxShape::String,
@@ -121,11 +128,19 @@ impl Command for SubCommand {
                     span,
                 }),
             },
+            Example {
+                description: "Convert duration to duration",
+                example: "420sec | into duration",
+                result: Some(Value::Duration {
+                    val: 7 * 60 * 1000 * 1000 * 1000,
+                    span,
+                }),
+            },
             Example {
                 description: "Convert duration to the requested duration as a string",
-                example: "420sec | into duration --convert min",
+                example: "420sec | into duration --convert ms",
                 result: Some(Value::String {
-                    val: "7 min".to_string(),
+                    val: "420000 ms".to_string(),
                     span,
                 }),
             },
diff --git a/crates/nu-command/src/conversions/into/filesize.rs b/crates/nu-command/src/conversions/into/filesize.rs
index 120e2eb1dd..545d3e3420 100644
--- a/crates/nu-command/src/conversions/into/filesize.rs
+++ b/crates/nu-command/src/conversions/into/filesize.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,12 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("into filesize")
+            .input_output_types(vec![
+                (Type::Int, Type::Filesize),
+                (Type::Number, Type::Filesize),
+                (Type::String, Type::Filesize),
+                (Type::Filesize, Type::Filesize),
+            ])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/conversions/into/int.rs b/crates/nu-command/src/conversions/into/int.rs
index 22a1d873b9..2cec85cc52 100644
--- a/crates/nu-command/src/conversions/into/int.rs
+++ b/crates/nu-command/src/conversions/into/int.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 struct Arguments {
@@ -28,6 +28,16 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("into int")
+            .input_output_types(vec![
+                (Type::String, Type::Int),
+                (Type::Number, Type::Int),
+                (Type::Bool, Type::Int),
+                // Unix timestamp in seconds
+                (Type::Date, Type::Int),
+                // TODO: Users should do this by dividing a Filesize by a Filesize explicitly
+                (Type::Filesize, Type::Int),
+            ])
+            .vectorizes_over_list(true)
             .named("radix", SyntaxShape::Number, "radix of integer", Some('r'))
             .switch("little-endian", "use little-endian byte decoding", None)
             .rest(
diff --git a/crates/nu-command/src/conversions/into/string.rs b/crates/nu-command/src/conversions/into/string.rs
index 8eacabfdd0..41d0d02de1 100644
--- a/crates/nu-command/src/conversions/into/string.rs
+++ b/crates/nu-command/src/conversions/into/string.rs
@@ -4,7 +4,7 @@ use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
     into_code, Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature,
-    Span, SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 use nu_utils::get_system_locale;
 use num_format::ToFormattedString;
@@ -32,6 +32,16 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("into string")
+            .input_output_types(vec![
+                (Type::Binary, Type::String),
+                (Type::Int, Type::String),
+                (Type::Number, Type::String),
+                (Type::String, Type::String),
+                (Type::Bool, Type::String),
+                (Type::Filesize, Type::String),
+                (Type::Date, Type::String),
+            ])
+            .allow_variants_without_examples(true) // https://github.com/nushell/nushell/issues/7032
             // FIXME - need to support column paths
             .rest(
                 "rest",
@@ -135,11 +145,12 @@ impl Command for SubCommand {
                     span: Span::test_data(),
                 }),
             },
-            Example {
-                description: "convert date to string",
-                example: "date now | into string",
-                result: None,
-            },
+            // TODO: This should work but does not; see https://github.com/nushell/nushell/issues/7032
+            // Example {
+            //     description: "convert date to string",
+            //     example: "'2020-10-10 10:00:00 +02:00' | into datetime | into string",
+            //     result: Some(Value::test_string("Sat Oct 10 10:00:00 2020")),
+            // },
             Example {
                 description: "convert filepath to string",
                 example: "ls Cargo.toml | get name | into string",
@@ -147,8 +158,8 @@ impl Command for SubCommand {
             },
             Example {
                 description: "convert filesize to string",
-                example: "ls Cargo.toml | get size | into string",
-                result: None,
+                example: "1KiB | into string",
+                result: Some(Value::test_string("1,024 B")),
             },
         ]
     }
diff --git a/crates/nu-command/src/core_commands/alias.rs b/crates/nu-command/src/core_commands/alias.rs
index 2377c0848e..0b81e43590 100644
--- a/crates/nu-command/src/core_commands/alias.rs
+++ b/crates/nu-command/src/core_commands/alias.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct Alias;
@@ -16,6 +16,7 @@ impl Command for Alias {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("alias")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("name", SyntaxShape::String, "name of the alias")
             .required(
                 "initial_value",
@@ -53,12 +54,12 @@ impl Command for Alias {
             Example {
                 description: "Alias ll to ls -l",
                 example: "alias ll = ls -l",
-                result: None,
+                result: Some(Value::nothing(Span::test_data())),
             },
             Example {
                 description: "Make an alias that makes a list of all custom commands",
                 example: "alias customs = ($nu.scope.commands | where is_custom | get command)",
-                result: None,
+                result: Some(Value::nothing(Span::test_data())),
             },
         ]
     }
diff --git a/crates/nu-command/src/core_commands/ast.rs b/crates/nu-command/src/core_commands/ast.rs
index f61719fde0..5999018ac6 100644
--- a/crates/nu-command/src/core_commands/ast.rs
+++ b/crates/nu-command/src/core_commands/ast.rs
@@ -3,7 +3,8 @@ use nu_parser::parse;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack, StateWorkingSet},
-    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +21,7 @@ impl Command for Ast {
 
     fn signature(&self) -> Signature {
         Signature::build("ast")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required(
                 "pipeline",
                 SyntaxShape::String,
@@ -50,17 +52,17 @@ impl Command for Ast {
             Example {
                 description: "Print the ast of a string",
                 example: "ast 'hello'",
-                result: None,
+                result: Some(Value::nothing(Span::test_data())),
             },
             Example {
                 description: "Print the ast of a pipeline",
                 example: "ast 'ls | where name =~ README'",
-                result: None,
+                result: Some(Value::nothing(Span::test_data())),
             },
             Example {
                 description: "Print the ast of a pipeline with an error",
                 example: "ast 'for x in 1..10 { echo $x '",
-                result: None,
+                result: Some(Value::nothing(Span::test_data())),
             },
         ]
     }
diff --git a/crates/nu-command/src/core_commands/commandline.rs b/crates/nu-command/src/core_commands/commandline.rs
index 3561d21292..f371613c5e 100644
--- a/crates/nu-command/src/core_commands/commandline.rs
+++ b/crates/nu-command/src/core_commands/commandline.rs
@@ -4,7 +4,7 @@ use nu_protocol::engine::ReplOperation;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
 use nu_protocol::IntoPipelineData;
-use nu_protocol::{PipelineData, ShellError, Signature, SyntaxShape, Value};
+use nu_protocol::{PipelineData, ShellError, Signature, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct Commandline;
@@ -16,6 +16,7 @@ impl Command for Commandline {
 
     fn signature(&self) -> Signature {
         Signature::build("commandline")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .switch(
                 "append",
                 "appends the string to the end of the buffer",
diff --git a/crates/nu-command/src/core_commands/debug.rs b/crates/nu-command/src/core_commands/debug.rs
index fd2e674746..8084208baf 100644
--- a/crates/nu-command/src/core_commands/debug.rs
+++ b/crates/nu-command/src/core_commands/debug.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct Debug;
@@ -15,11 +15,17 @@ impl Command for Debug {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("debug").category(Category::Core).switch(
-            "raw",
-            "Prints the raw value representation",
-            Some('r'),
-        )
+        Signature::build("debug")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::String)),
+                ),
+                (Type::Table(vec![]), Type::List(Box::new(Type::String))),
+                (Type::Any, Type::String),
+            ])
+            .category(Category::Core)
+            .switch("raw", "Prints the raw value representation", Some('r'))
     }
 
     fn run(
@@ -54,12 +60,20 @@ impl Command for Debug {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Print the value of a string",
+                description: "Debug print a string",
                 example: "'hello' | debug",
                 result: Some(Value::test_string("hello")),
             },
             Example {
-                description: "Print the value of a table",
+                description: "Debug print a list",
+                example: "['hello'] | debug",
+                result: Some(Value::List {
+                    vals: vec![Value::test_string("hello")],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Debug print a table",
                 example: "echo [[version patch]; [0.1.0 false] [0.1.1 true] [0.2.0 false]] | debug",
                 result: Some(Value::List {
                     vals: vec![
diff --git a/crates/nu-command/src/core_commands/def.rs b/crates/nu-command/src/core_commands/def.rs
index 19f2928a07..f812efe0d3 100644
--- a/crates/nu-command/src/core_commands/def.rs
+++ b/crates/nu-command/src/core_commands/def.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct Def;
@@ -16,6 +16,7 @@ impl Command for Def {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("def")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("def_name", SyntaxShape::String, "definition name")
             .required("params", SyntaxShape::Signature, "parameters")
             .required(
diff --git a/crates/nu-command/src/core_commands/def_env.rs b/crates/nu-command/src/core_commands/def_env.rs
index 1115a715f8..4cc0a668f0 100644
--- a/crates/nu-command/src/core_commands/def_env.rs
+++ b/crates/nu-command/src/core_commands/def_env.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct DefEnv;
@@ -16,6 +16,7 @@ impl Command for DefEnv {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("def-env")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("def_name", SyntaxShape::String, "definition name")
             .required("params", SyntaxShape::Signature, "parameters")
             .required(
diff --git a/crates/nu-command/src/core_commands/describe.rs b/crates/nu-command/src/core_commands/describe.rs
index 88b7a1dffa..e44268ee9e 100644
--- a/crates/nu-command/src/core_commands/describe.rs
+++ b/crates/nu-command/src/core_commands/describe.rs
@@ -1,7 +1,7 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,7 +17,9 @@ impl Command for Describe {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("describe").category(Category::Core)
+        Signature::build("describe")
+            .input_output_types(vec![(Type::Any, Type::String)])
+            .category(Category::Core)
     }
 
     fn run(
diff --git a/crates/nu-command/src/core_commands/do_.rs b/crates/nu-command/src/core_commands/do_.rs
index 5fdd9afc10..69efb4d6ce 100644
--- a/crates/nu-command/src/core_commands/do_.rs
+++ b/crates/nu-command/src/core_commands/do_.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, ListStream, PipelineData, RawStream, ShellError, Signature, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +20,7 @@ impl Command for Do {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("do")
+            .input_output_types(vec![(Type::Any, Type::Any)])
             .required("block", SyntaxShape::Any, "the block to run")
             .switch(
                 "ignore-errors",
@@ -197,8 +198,13 @@ impl Command for Do {
             },
             Example {
                 description: "Run the block, with a positional parameter",
-                example: r#"do {|x| 100 + $x } 50"#,
-                result: Some(Value::test_int(150)),
+                example: r#"do {|x| 100 + $x } 77"#,
+                result: Some(Value::test_int(177)),
+            },
+            Example {
+                description: "Run the block, with input",
+                example: r#"77 | do {|x| 100 + $in }"#,
+                result: None, // TODO: returns 177
             },
         ]
     }
diff --git a/crates/nu-command/src/core_commands/echo.rs b/crates/nu-command/src/core_commands/echo.rs
index c5d2c38e5b..21f6d266e6 100644
--- a/crates/nu-command/src/core_commands/echo.rs
+++ b/crates/nu-command/src/core_commands/echo.rs
@@ -2,7 +2,8 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, ListStream, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, ListStream, PipelineData, ShellError, Signature, Span, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +20,7 @@ impl Command for Echo {
 
     fn signature(&self) -> Signature {
         Signature::build("echo")
+            .input_output_types(vec![(Type::Nothing, Type::Any)])
             .rest("rest", SyntaxShape::Any, "the values to echo")
             .category(Category::Core)
     }
diff --git a/crates/nu-command/src/core_commands/export.rs b/crates/nu-command/src/core_commands/export.rs
index 6dc7c5f741..f5e2c40e05 100644
--- a/crates/nu-command/src/core_commands/export.rs
+++ b/crates/nu-command/src/core_commands/export.rs
@@ -2,7 +2,7 @@ use nu_engine::get_full_help;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, PipelineData, Signature, Span, Value,
+    Category, Example, IntoPipelineData, PipelineData, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,7 +14,9 @@ impl Command for ExportCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("export").category(Category::Core)
+        Signature::build("export")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .category(Category::Core)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/core_commands/export_alias.rs b/crates/nu-command/src/core_commands/export_alias.rs
index 9f31064936..04f3cba424 100644
--- a/crates/nu-command/src/core_commands/export_alias.rs
+++ b/crates/nu-command/src/core_commands/export_alias.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type};
 
 #[derive(Clone)]
 pub struct ExportAlias;
@@ -16,6 +16,7 @@ impl Command for ExportAlias {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("export alias")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("name", SyntaxShape::String, "name of the alias")
             .required(
                 "initial_value",
diff --git a/crates/nu-command/src/core_commands/export_def.rs b/crates/nu-command/src/core_commands/export_def.rs
index 1ab327100c..dce5c81d73 100644
--- a/crates/nu-command/src/core_commands/export_def.rs
+++ b/crates/nu-command/src/core_commands/export_def.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct ExportDef;
@@ -16,6 +16,7 @@ impl Command for ExportDef {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("export def")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("name", SyntaxShape::String, "definition name")
             .required("params", SyntaxShape::Signature, "parameters")
             .required(
diff --git a/crates/nu-command/src/core_commands/export_def_env.rs b/crates/nu-command/src/core_commands/export_def_env.rs
index 4ea55cd1e2..15ad86cdcb 100644
--- a/crates/nu-command/src/core_commands/export_def_env.rs
+++ b/crates/nu-command/src/core_commands/export_def_env.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct ExportDefEnv;
@@ -16,6 +16,7 @@ impl Command for ExportDefEnv {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("export def-env")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("name", SyntaxShape::String, "definition name")
             .required("params", SyntaxShape::Signature, "parameters")
             .required(
diff --git a/crates/nu-command/src/core_commands/export_extern.rs b/crates/nu-command/src/core_commands/export_extern.rs
index b718a80af8..cbca9ed407 100644
--- a/crates/nu-command/src/core_commands/export_extern.rs
+++ b/crates/nu-command/src/core_commands/export_extern.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type};
 
 #[derive(Clone)]
 pub struct ExportExtern;
@@ -16,6 +16,7 @@ impl Command for ExportExtern {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("export extern")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("def_name", SyntaxShape::String, "definition name")
             .required("params", SyntaxShape::Signature, "parameters")
             .category(Category::Core)
diff --git a/crates/nu-command/src/core_commands/export_use.rs b/crates/nu-command/src/core_commands/export_use.rs
index 48676a647d..61b26aafab 100644
--- a/crates/nu-command/src/core_commands/export_use.rs
+++ b/crates/nu-command/src/core_commands/export_use.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct ExportUse;
@@ -16,6 +16,7 @@ impl Command for ExportUse {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("export use")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("pattern", SyntaxShape::ImportPattern, "import pattern")
             .category(Category::Core)
     }
diff --git a/crates/nu-command/src/core_commands/extern_.rs b/crates/nu-command/src/core_commands/extern_.rs
index 51a89bb624..1bef269b23 100644
--- a/crates/nu-command/src/core_commands/extern_.rs
+++ b/crates/nu-command/src/core_commands/extern_.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type};
 
 #[derive(Clone)]
 pub struct Extern;
@@ -16,6 +16,7 @@ impl Command for Extern {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("extern")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("def_name", SyntaxShape::String, "definition name")
             .required("params", SyntaxShape::Signature, "parameters")
             .category(Category::Core)
diff --git a/crates/nu-command/src/core_commands/for_.rs b/crates/nu-command/src/core_commands/for_.rs
index 58d4394a58..bf807dd5a7 100644
--- a/crates/nu-command/src/core_commands/for_.rs
+++ b/crates/nu-command/src/core_commands/for_.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, ListStream, PipelineData, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +20,7 @@ impl Command for For {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("for")
+            .input_output_types(vec![(Type::Nothing, Type::List(Box::new(Type::Any)))])
             .required(
                 "var_name",
                 SyntaxShape::VarWithOptType,
diff --git a/crates/nu-command/src/core_commands/help.rs b/crates/nu-command/src/core_commands/help.rs
index 11d47ec4bd..c98dc44c1a 100644
--- a/crates/nu-command/src/core_commands/help.rs
+++ b/crates/nu-command/src/core_commands/help.rs
@@ -1,4 +1,5 @@
 use fancy_regex::Regex;
+use itertools::Itertools;
 use nu_ansi_term::{
     Color::{Default, Red, White},
     Style,
@@ -9,7 +10,7 @@ use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
     span, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 use std::borrow::Borrow;
 #[derive(Clone)]
@@ -22,6 +23,7 @@ impl Command for Help {
 
     fn signature(&self) -> Signature {
         Signature::build("help")
+            .input_output_types(vec![(Type::Nothing, Type::String)])
             .rest(
                 "rest",
                 SyntaxShape::String,
@@ -162,6 +164,16 @@ fn help(
                     span: head,
                 });
 
+                cols.push("signatures".into());
+                vals.push(Value::String {
+                    val: sig
+                        .input_output_types
+                        .iter()
+                        .map(|(i, o)| format!("{:?} => {:?}", i.to_shape(), o.to_shape()))
+                        .join("\n"),
+                    span: head,
+                });
+
                 cols.push("search_terms".into());
                 vals.push(if search_terms.is_empty() {
                     Value::nothing(head)
@@ -259,6 +271,16 @@ fn help(
                     span: head,
                 });
 
+                cols.push("signatures".into());
+                vals.push(Value::String {
+                    val: sig
+                        .input_output_types
+                        .iter()
+                        .map(|(i, o)| format!("{:?} => {:?}", i.to_shape(), o.to_shape()))
+                        .join("\n"),
+                    span: head,
+                });
+
                 cols.push("search_terms".into());
                 vals.push(if search_terms.is_empty() {
                     Value::nothing(head)
diff --git a/crates/nu-command/src/core_commands/hide.rs b/crates/nu-command/src/core_commands/hide.rs
index 096da23cbc..a79858953d 100644
--- a/crates/nu-command/src/core_commands/hide.rs
+++ b/crates/nu-command/src/core_commands/hide.rs
@@ -1,7 +1,7 @@
 use nu_protocol::ast::{Call, Expr, Expression};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,6 +14,7 @@ impl Command for Hide {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("hide")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("pattern", SyntaxShape::ImportPattern, "import pattern")
             .category(Category::Core)
     }
diff --git a/crates/nu-command/src/core_commands/hide_env.rs b/crates/nu-command/src/core_commands/hide_env.rs
index 3bee3d77c1..f446b5f1d3 100644
--- a/crates/nu-command/src/core_commands/hide_env.rs
+++ b/crates/nu-command/src/core_commands/hide_env.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     did_you_mean, Category, Example, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,7 @@ impl Command for HideEnv {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("hide-env")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .rest(
                 "name",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/core_commands/if_.rs b/crates/nu-command/src/core_commands/if_.rs
index 4821c54d4c..ebf9756464 100644
--- a/crates/nu-command/src/core_commands/if_.rs
+++ b/crates/nu-command/src/core_commands/if_.rs
@@ -2,7 +2,7 @@ use nu_engine::{eval_block, eval_expression, eval_expression_with_input, CallExt
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, FromValue, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, FromValue, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,7 @@ impl Command for If {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("if")
+            .input_output_types(vec![(Type::Any, Type::Any)])
             .required("cond", SyntaxShape::Expression, "condition to check")
             .required(
                 "then_block",
diff --git a/crates/nu-command/src/core_commands/ignore.rs b/crates/nu-command/src/core_commands/ignore.rs
index 682506f404..610978d156 100644
--- a/crates/nu-command/src/core_commands/ignore.rs
+++ b/crates/nu-command/src/core_commands/ignore.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct Ignore;
@@ -15,7 +15,9 @@ impl Command for Ignore {
     }
 
     fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("ignore").category(Category::Core)
+        Signature::build("ignore")
+            .input_output_types(vec![(Type::Any, Type::Nothing)])
+            .category(Category::Core)
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -37,7 +39,7 @@ impl Command for Ignore {
         vec![Example {
             description: "Ignore the output of an echo command",
             example: "echo done | ignore",
-            result: None,
+            result: Some(Value::nothing(Span::test_data())),
         }]
     }
 }
diff --git a/crates/nu-command/src/core_commands/let_.rs b/crates/nu-command/src/core_commands/let_.rs
index 3b750b9940..23dcb70117 100644
--- a/crates/nu-command/src/core_commands/let_.rs
+++ b/crates/nu-command/src/core_commands/let_.rs
@@ -1,7 +1,7 @@
 use nu_engine::eval_expression_with_input;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type};
 
 #[derive(Clone)]
 pub struct Let;
@@ -17,6 +17,8 @@ impl Command for Let {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("let")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
             .required("var_name", SyntaxShape::VarWithOptType, "variable name")
             .required(
                 "initial_value",
diff --git a/crates/nu-command/src/core_commands/metadata.rs b/crates/nu-command/src/core_commands/metadata.rs
index 3697236b9e..04fcd2d46e 100644
--- a/crates/nu-command/src/core_commands/metadata.rs
+++ b/crates/nu-command/src/core_commands/metadata.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, Expr, Expression};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, DataSource, Example, IntoPipelineData, PipelineData, PipelineMetadata, Signature,
-    Span, SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +20,8 @@ impl Command for Metadata {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("metadata")
+            .input_output_types(vec![(Type::Nothing, Type::Record(vec![]))])
+            .allow_variants_without_examples(true)
             .optional(
                 "expression",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/core_commands/module.rs b/crates/nu-command/src/core_commands/module.rs
index 93edb68b91..c01dc30d12 100644
--- a/crates/nu-command/src/core_commands/module.rs
+++ b/crates/nu-command/src/core_commands/module.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct Module;
@@ -16,6 +16,7 @@ impl Command for Module {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("module")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("module_name", SyntaxShape::String, "module name")
             .required(
                 "block",
diff --git a/crates/nu-command/src/core_commands/register.rs b/crates/nu-command/src/core_commands/register.rs
index d175480b56..eaf6ee342a 100644
--- a/crates/nu-command/src/core_commands/register.rs
+++ b/crates/nu-command/src/core_commands/register.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type};
 
 #[derive(Clone)]
 pub struct Register;
@@ -16,6 +16,7 @@ impl Command for Register {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("register")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required(
                 "plugin",
                 SyntaxShape::Filepath,
diff --git a/crates/nu-command/src/core_commands/use_.rs b/crates/nu-command/src/core_commands/use_.rs
index 02155f2330..73a13d290e 100644
--- a/crates/nu-command/src/core_commands/use_.rs
+++ b/crates/nu-command/src/core_commands/use_.rs
@@ -2,7 +2,7 @@ use nu_engine::{eval_block, find_in_dirs_env, redirect_env};
 use nu_protocol::ast::{Call, Expr, Expression};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,7 @@ impl Command for Use {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("use")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("pattern", SyntaxShape::ImportPattern, "import pattern")
             .category(Category::Core)
     }
diff --git a/crates/nu-command/src/core_commands/version.rs b/crates/nu-command/src/core_commands/version.rs
index b01a683c83..d6f3148739 100644
--- a/crates/nu-command/src/core_commands/version.rs
+++ b/crates/nu-command/src/core_commands/version.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Example, IntoPipelineData, PipelineData, ShellError, Signature, Value};
+use nu_protocol::{Example, IntoPipelineData, PipelineData, ShellError, Signature, Type, Value};
 
 pub mod shadow {
     include!(concat!(env!("OUT_DIR"), "/shadow.rs"));
@@ -16,6 +16,8 @@ impl Command for Version {
 
     fn signature(&self) -> Signature {
         Signature::build("version")
+            .input_output_types(vec![(Type::Nothing, Type::Record(vec![]))])
+            .allow_variants_without_examples(true)
     }
 
     fn usage(&self) -> &str {
@@ -215,3 +217,13 @@ fn features_enabled() -> Vec<String> {
 
     names
 }
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test_examples() {
+        use super::Version;
+        use crate::test_examples;
+        test_examples(Version {})
+    }
+}
diff --git a/crates/nu-command/src/date/format.rs b/crates/nu-command/src/date/format.rs
index c7032f9f70..55a76b7425 100644
--- a/crates/nu-command/src/date/format.rs
+++ b/crates/nu-command/src/date/format.rs
@@ -4,7 +4,8 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
+    Value,
 };
 use nu_utils::locale::get_system_locale_string;
 use std::fmt::{Display, Write};
@@ -21,6 +22,11 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("date format")
+            .input_output_types(vec![
+                (Type::Date, Type::String),
+                (Type::String, Type::String),
+            ])
+            .allow_variants_without_examples(true) // https://github.com/nushell/nushell/issues/7032
             .switch("list", "lists strftime cheatsheet", Some('l'))
             .optional(
                 "format string",
@@ -66,8 +72,18 @@ impl Command for SubCommand {
 
     fn examples(&self) -> Vec<Example> {
         vec![
+            // TODO: This should work but does not; see https://github.com/nushell/nushell/issues/7032
+            // Example {
+            //     description: "Format a given date-time using the default format (RFC 2822).",
+            //     example: r#"'2021-10-22 20:00:12 +01:00' | into datetime | date format"#,
+            //     result: Some(Value::String {
+            //         val: "Fri, 22 Oct 2021 20:00:12 +0100".to_string(),
+            //         span: Span::test_data(),
+            //     }),
+            // },
             Example {
-                description: "Format a given date using the default format (RFC 2822).",
+                description:
+                    "Format a given date-time as a string using the default format (RFC 2822).",
                 example: r#""2021-10-22 20:00:12 +01:00" | date format"#,
                 result: Some(Value::String {
                     val: "Fri, 22 Oct 2021 20:00:12 +0100".to_string(),
@@ -75,13 +91,13 @@ impl Command for SubCommand {
                 }),
             },
             Example {
-                description: "Format a given date using a given format string.",
-                example: "date format '%Y-%m-%d'",
+                description: "Format the current date-time using a given format string.",
+                example: r#"date now | date format "%Y-%m-%d %H:%M:%S""#,
                 result: None,
             },
             Example {
-                description: "Format a given date using a given format string.",
-                example: r#"date format "%Y-%m-%d %H:%M:%S""#,
+                description: "Format the current date using a given format string.",
+                example: r#"date now | date format "%Y-%m-%d %H:%M:%S""#,
                 result: None,
             },
             Example {
diff --git a/crates/nu-command/src/date/humanize.rs b/crates/nu-command/src/date/humanize.rs
index 7b070a7334..91b0cab7a8 100644
--- a/crates/nu-command/src/date/humanize.rs
+++ b/crates/nu-command/src/date/humanize.rs
@@ -3,7 +3,7 @@ use chrono::{DateTime, FixedOffset, Local};
 use chrono_humanize::HumanTime;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 #[derive(Clone)]
 pub struct SubCommand;
 
@@ -13,7 +13,13 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("date humanize").category(Category::Date)
+        Signature::build("date humanize")
+            .input_output_types(vec![
+                (Type::Date, Type::String),
+                (Type::String, Type::String),
+            ])
+            .allow_variants_without_examples(true)
+            .category(Category::Date)
     }
 
     fn usage(&self) -> &str {
@@ -45,21 +51,11 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![
-            Example {
-                description: "Print a 'humanized' format for the date, relative to now.",
-                example: "date humanize",
-                result: Some(Value::String {
-                    val: "now".to_string(),
-                    span: Span::test_data(),
-                }),
-            },
-            Example {
-                description: "Print a 'humanized' format for the date, relative to now.",
-                example: r#""2021-10-22 20:00:12 +01:00" | date humanize"#,
-                result: None,
-            },
-        ]
+        vec![Example {
+            description: "Print a 'humanized' format for the date, relative to now.",
+            example: r#""2021-10-22 20:00:12 +01:00" | date humanize"#,
+            result: None,
+        }]
     }
 }
 
diff --git a/crates/nu-command/src/date/list_timezone.rs b/crates/nu-command/src/date/list_timezone.rs
index f2827d351f..3945e1cebc 100644
--- a/crates/nu-command/src/date/list_timezone.rs
+++ b/crates/nu-command/src/date/list_timezone.rs
@@ -2,7 +2,7 @@ use chrono_tz::TZ_VARIANTS;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoInterruptiblePipelineData, PipelineData, Signature, Span, Value,
+    Category, Example, IntoInterruptiblePipelineData, PipelineData, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,7 +14,9 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("date list-timezone").category(Category::Date)
+        Signature::build("date list-timezone")
+            .input_output_types(vec![(Type::Nothing, Type::Table(vec![]))])
+            .category(Category::Date)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/date/now.rs b/crates/nu-command/src/date/now.rs
index fd2d8f4ecb..7dd6a8be35 100644
--- a/crates/nu-command/src/date/now.rs
+++ b/crates/nu-command/src/date/now.rs
@@ -1,7 +1,7 @@
 use chrono::Local;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, IntoPipelineData, PipelineData, Signature, Value};
+use nu_protocol::{Category, Example, IntoPipelineData, PipelineData, Signature, Type, Value};
 #[derive(Clone)]
 pub struct SubCommand;
 
@@ -11,7 +11,9 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("date now").category(Category::Date)
+        Signature::build("date now")
+            .input_output_types(vec![(Type::Nothing, Type::Date)])
+            .category(Category::Date)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/date/to_record.rs b/crates/nu-command/src/date/to_record.rs
index 44633943f7..96ae338054 100644
--- a/crates/nu-command/src/date/to_record.rs
+++ b/crates/nu-command/src/date/to_record.rs
@@ -2,6 +2,7 @@ use crate::date::utils::parse_date_from_string;
 use chrono::{DateTime, Datelike, FixedOffset, Local, Timelike};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::Type;
 use nu_protocol::{
     Category, Example, PipelineData, ShellError::DatetimeParseError, Signature, Span, Value,
 };
@@ -15,11 +16,17 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("date to-record").category(Category::Date)
+        Signature::build("date to-record")
+            .input_output_types(vec![
+                (Type::Date, Type::Record(vec![])),
+                (Type::String, Type::Record(vec![])),
+            ])
+            .allow_variants_without_examples(true) // https://github.com/nushell/nushell/issues/7032
+            .category(Category::Date)
     }
 
     fn usage(&self) -> &str {
-        "Convert the date into a structured table."
+        "Convert the date into a record."
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -38,46 +45,54 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
+        let example_result_1 = || {
+            let span = Span::test_data();
+            let cols = vec![
+                "year".into(),
+                "month".into(),
+                "day".into(),
+                "hour".into(),
+                "minute".into(),
+                "second".into(),
+                "timezone".into(),
+            ];
+            let vals = vec![
+                Value::Int { val: 2020, span },
+                Value::Int { val: 4, span },
+                Value::Int { val: 12, span },
+                Value::Int { val: 22, span },
+                Value::Int { val: 10, span },
+                Value::Int { val: 57, span },
+                Value::String {
+                    val: "+02:00".to_string(),
+                    span,
+                },
+            ];
+            Some(Value::Record { cols, vals, span })
+        };
+
         vec![
             Example {
-                description: "Convert the current date into a structured table.",
-                example: "date to-table",
+                description: "Convert the current date into a record.",
+                example: "date to-record",
                 result: None,
             },
             Example {
-                description: "Convert the current date into a structured table.",
+                description: "Convert the current date into a record.",
                 example: "date now | date to-record",
                 result: None,
             },
             Example {
-                description: "Convert a given date into a structured table.",
-                example: " '2020-04-12 22:10:57 +0200' | date to-record",
-                result: {
-                    let span = Span::test_data();
-                    let cols = vec![
-                        "year".into(),
-                        "month".into(),
-                        "day".into(),
-                        "hour".into(),
-                        "minute".into(),
-                        "second".into(),
-                        "timezone".into(),
-                    ];
-                    let vals = vec![
-                        Value::Int { val: 2020, span },
-                        Value::Int { val: 4, span },
-                        Value::Int { val: 12, span },
-                        Value::Int { val: 22, span },
-                        Value::Int { val: 10, span },
-                        Value::Int { val: 57, span },
-                        Value::String {
-                            val: "+02:00".to_string(),
-                            span,
-                        },
-                    ];
-                    Some(Value::Record { cols, vals, span })
-                },
+                description: "Convert a date string into a record.",
+                example: "'2020-04-12 22:10:57 +0200' | date to-record",
+                result: example_result_1(),
             },
+            // TODO: This should work but does not; see https://github.com/nushell/nushell/issues/7032
+            // Example {
+            //     description: "Convert a date into a record.",
+            //     example: "'2020-04-12 22:10:57 +0200' | into datetime | date to-record",
+            //     result: example_result_1(),
+            // },
         ]
     }
 }
diff --git a/crates/nu-command/src/date/to_table.rs b/crates/nu-command/src/date/to_table.rs
index 4de85ac6e6..d710209532 100644
--- a/crates/nu-command/src/date/to_table.rs
+++ b/crates/nu-command/src/date/to_table.rs
@@ -2,6 +2,7 @@ use crate::date::utils::parse_date_from_string;
 use chrono::{DateTime, Datelike, FixedOffset, Local, Timelike};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::Type;
 use nu_protocol::{
     Category, Example, PipelineData, ShellError::DatetimeParseError, Signature, Span, Value,
 };
@@ -15,7 +16,13 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("date to-table").category(Category::Date)
+        Signature::build("date to-table")
+            .input_output_types(vec![
+                (Type::Date, Type::Table(vec![])),
+                (Type::String, Type::Table(vec![])),
+            ])
+            .allow_variants_without_examples(true) // https://github.com/nushell/nushell/issues/7032
+            .category(Category::Date)
     }
 
     fn usage(&self) -> &str {
@@ -38,49 +45,57 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
+        let example_result_1 = || {
+            let span = Span::test_data();
+            let cols = vec![
+                "year".into(),
+                "month".into(),
+                "day".into(),
+                "hour".into(),
+                "minute".into(),
+                "second".into(),
+                "timezone".into(),
+            ];
+            let vals = vec![
+                Value::Int { val: 2020, span },
+                Value::Int { val: 4, span },
+                Value::Int { val: 12, span },
+                Value::Int { val: 22, span },
+                Value::Int { val: 10, span },
+                Value::Int { val: 57, span },
+                Value::String {
+                    val: "+02:00".to_string(),
+                    span,
+                },
+            ];
+            Some(Value::List {
+                vals: vec![Value::Record { cols, vals, span }],
+                span,
+            })
+        };
+
         vec![
             Example {
-                description: "Convert the date into a structured table.",
+                description: "Convert the current date into a table.",
                 example: "date to-table",
                 result: None,
             },
             Example {
-                description: "Convert the date into a structured table.",
+                description: "Convert the date into a table.",
                 example: "date now | date to-table",
                 result: None,
             },
             Example {
-                description: "Convert a given date into a structured table.",
-                example: " '2020-04-12 22:10:57 +0200' | date to-table",
-                result: {
-                    let span = Span::test_data();
-                    let cols = vec![
-                        "year".into(),
-                        "month".into(),
-                        "day".into(),
-                        "hour".into(),
-                        "minute".into(),
-                        "second".into(),
-                        "timezone".into(),
-                    ];
-                    let vals = vec![
-                        Value::Int { val: 2020, span },
-                        Value::Int { val: 4, span },
-                        Value::Int { val: 12, span },
-                        Value::Int { val: 22, span },
-                        Value::Int { val: 10, span },
-                        Value::Int { val: 57, span },
-                        Value::String {
-                            val: "+02:00".to_string(),
-                            span,
-                        },
-                    ];
-                    Some(Value::List {
-                        vals: vec![Value::Record { cols, vals, span }],
-                        span,
-                    })
-                },
+                description: "Convert a given date into a table.",
+                example: "'2020-04-12 22:10:57 +0200' | date to-table",
+                result: example_result_1(),
             },
+            // TODO: This should work but does not; see https://github.com/nushell/nushell/issues/7032
+            // Example {
+            //     description: "Convert a given date into a table.",
+            //     example: "'2020-04-12 22:10:57 +0200' | into datetime | date to-table",
+            //     result: example_result_1(),
+            // },
         ]
     }
 }
diff --git a/crates/nu-command/src/date/to_timezone.rs b/crates/nu-command/src/date/to_timezone.rs
index 9c690f6221..7a33c301e9 100644
--- a/crates/nu-command/src/date/to_timezone.rs
+++ b/crates/nu-command/src/date/to_timezone.rs
@@ -5,7 +5,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 use chrono::{FixedOffset, TimeZone};
@@ -20,6 +20,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("date to-timezone")
+            .input_output_types(vec![(Type::Date, Type::Date), (Type::String, Type::Date)])
+            .allow_variants_without_examples(true) // https://github.com/nushell/nushell/issues/7032
             .required("time zone", SyntaxShape::String, "time zone description")
             .category(Category::Date)
     }
@@ -62,6 +64,16 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
+        let example_result_1 = || {
+            let dt = FixedOffset::east(5 * 3600)
+                .ymd(2020, 10, 10)
+                .and_hms(13, 00, 00);
+            Some(Value::Date {
+                val: dt,
+                span: Span::test_data(),
+            })
+        };
+
         vec![
             Example {
                 description: "Get the current date in UTC+05:00",
@@ -81,19 +93,14 @@ impl Command for SubCommand {
             Example {
                 description: "Get the current date in Hawaii",
                 example: r#""2020-10-10 10:00:00 +02:00" | date to-timezone "+0500""#,
-                // result: None
-                // The following should be the result of the test, but it fails. Cannot figure it out why.
-                result: {
-                    let dt = FixedOffset::east(5 * 3600)
-                        .ymd(2020, 10, 10)
-                        .and_hms(13, 00, 00);
-
-                    Some(Value::Date {
-                        val: dt,
-                        span: Span::test_data(),
-                    })
-                },
+                result: example_result_1(),
             },
+            // TODO: This should work but does not; see https://github.com/nushell/nushell/issues/7032
+            // Example {
+            //     description: "Get the current date in Hawaii, from a datetime object",
+            //     example: r#""2020-10-10 10:00:00 +02:00" | into datetime | date to-timezone "+0500""#,
+            //     result: example_result_1(),
+            // },
         ]
     }
 }
diff --git a/crates/nu-command/src/env/export_env.rs b/crates/nu-command/src/env/export_env.rs
index 60635013d0..88003495b9 100644
--- a/crates/nu-command/src/env/export_env.rs
+++ b/crates/nu-command/src/env/export_env.rs
@@ -2,7 +2,7 @@ use nu_engine::{eval_block, redirect_env, CallExt};
 use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
-    Category, Example, PipelineData, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,7 @@ impl Command for ExportEnv {
 
     fn signature(&self) -> Signature {
         Signature::build("export-env")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required(
                 "block",
                 SyntaxShape::Block(Some(vec![])),
@@ -53,11 +54,20 @@ impl Command for ExportEnv {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Set an environment",
-            example: r#"export-env { let-env SPAM = 'eggs' }; $env.SPAM"#,
-            result: Some(Value::string("eggs", Span::test_data())),
-        }]
+        vec![
+            Example {
+                description: "Set an environment variable",
+                example: r#"export-env { let-env SPAM = 'eggs' }"#,
+                result: Some(Value::Nothing {
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Set an environment variable and examine its value",
+                example: r#"export-env { let-env SPAM = 'eggs' }; $env.SPAM"#,
+                result: Some(Value::string("eggs", Span::test_data())),
+            },
+        ]
     }
 }
 
diff --git a/crates/nu-command/src/env/with_env.rs b/crates/nu-command/src/env/with_env.rs
index 817b71a21c..a1f5b86e94 100644
--- a/crates/nu-command/src/env/with_env.rs
+++ b/crates/nu-command/src/env/with_env.rs
@@ -4,7 +4,7 @@ use nu_engine::{eval_block, CallExt};
 use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,7 @@ impl Command for WithEnv {
 
     fn signature(&self) -> Signature {
         Signature::build("with-env")
+            .input_output_types(vec![(Type::Any, Type::Any)])
             .required(
                 "variable",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/example_test.rs b/crates/nu-command/src/example_test.rs
index 0180262954..549afd5a0d 100644
--- a/crates/nu-command/src/example_test.rs
+++ b/crates/nu-command/src/example_test.rs
@@ -1,75 +1,206 @@
 #[cfg(test)]
-use nu_engine::eval_block;
-#[cfg(test)]
-use nu_parser::parse;
-#[cfg(test)]
-use nu_protocol::{
-    engine::{Command, EngineState, Stack, StateWorkingSet},
-    PipelineData, Span, Value,
-};
-
-#[cfg(test)]
-use crate::To;
-
-#[cfg(test)]
-use super::{
-    Ansi, Date, From, If, Into, LetEnv, Math, Path, Random, Split, SplitColumn, SplitRow, Str,
-    StrJoin, StrLength, StrReplace, Url, Wrap,
-};
+use nu_protocol::engine::Command;
 
 #[cfg(test)]
 pub fn test_examples(cmd: impl Command + 'static) {
-    use crate::BuildString;
+    test_examples::test_examples(cmd);
+}
 
-    let examples = cmd.examples();
-    let mut engine_state = Box::new(EngineState::new());
-
-    let delta = {
-        // Base functions that are needed for testing
-        // Try to keep this working set small to keep tests running as fast as possible
-        let mut working_set = StateWorkingSet::new(&*engine_state);
-        working_set.add_decl(Box::new(Str));
-        working_set.add_decl(Box::new(StrJoin));
-        working_set.add_decl(Box::new(StrLength));
-        working_set.add_decl(Box::new(StrReplace));
-        working_set.add_decl(Box::new(BuildString));
-        working_set.add_decl(Box::new(From));
-        working_set.add_decl(Box::new(If));
-        working_set.add_decl(Box::new(To));
-        working_set.add_decl(Box::new(Into));
-        working_set.add_decl(Box::new(Random));
-        working_set.add_decl(Box::new(Split));
-        working_set.add_decl(Box::new(SplitColumn));
-        working_set.add_decl(Box::new(SplitRow));
-        working_set.add_decl(Box::new(Math));
-        working_set.add_decl(Box::new(Path));
-        working_set.add_decl(Box::new(Date));
-        working_set.add_decl(Box::new(Url));
-        working_set.add_decl(Box::new(Ansi));
-        working_set.add_decl(Box::new(Wrap));
-        working_set.add_decl(Box::new(LetEnv));
-
-        use super::Echo;
-        working_set.add_decl(Box::new(Echo));
-        // Adding the command that is being tested to the working set
-        working_set.add_decl(Box::new(cmd));
-
-        working_set.render()
+#[cfg(test)]
+mod test_examples {
+    use super::super::{
+        Ansi, BuildString, Date, Echo, From, If, Into, LetEnv, Math, Path, Random, Split,
+        SplitColumn, SplitRow, Str, StrJoin, StrLength, StrReplace, Url, Wrap,
     };
+    use crate::To;
+    use itertools::Itertools;
+    use nu_engine;
+    use nu_parser;
+    use nu_protocol::{
+        ast::Block,
+        engine::{Command, EngineState, Stack, StateDelta, StateWorkingSet},
+        Example, PipelineData, Signature, Span, Type, Value,
+    };
+    use std::{collections::HashSet, path::PathBuf};
 
-    let cwd = std::env::current_dir().expect("Could not get current working directory.");
+    pub fn test_examples(cmd: impl Command + 'static) {
+        let examples = cmd.examples();
+        let signature = cmd.signature();
+        let mut engine_state = make_engine_state(cmd.clone_box());
 
-    engine_state
-        .merge_delta(delta)
-        .expect("Error merging delta");
+        let cwd = std::env::current_dir().expect("Could not get current working directory.");
 
-    for example in examples {
-        // Skip tests that don't have results to compare to
-        if example.result.is_none() {
-            continue;
+        let mut witnessed_type_transformations = HashSet::<(Type, Type)>::new();
+
+        for example in examples {
+            if example.result.is_none() {
+                continue;
+            }
+            witnessed_type_transformations.extend(
+                check_example_input_and_output_types_match_command_signature(
+                    &example,
+                    &cwd,
+                    &mut make_engine_state(cmd.clone_box()),
+                    &signature.input_output_types,
+                    signature.operates_on_cell_paths(),
+                    signature.vectorizes_over_list,
+                ),
+            );
+            check_example_evaluates_to_expected_output(&example, &cwd, &mut engine_state);
         }
-        let start = std::time::Instant::now();
 
+        check_all_signature_input_output_types_entries_have_examples(
+            signature,
+            witnessed_type_transformations,
+        );
+    }
+
+    fn make_engine_state(cmd: Box<dyn Command>) -> Box<EngineState> {
+        let mut engine_state = Box::new(EngineState::new());
+
+        let delta = {
+            // Base functions that are needed for testing
+            // Try to keep this working set small to keep tests running as fast as possible
+            let mut working_set = StateWorkingSet::new(&*engine_state);
+            working_set.add_decl(Box::new(Str));
+            working_set.add_decl(Box::new(StrJoin));
+            working_set.add_decl(Box::new(StrLength));
+            working_set.add_decl(Box::new(StrReplace));
+            working_set.add_decl(Box::new(BuildString));
+            working_set.add_decl(Box::new(From));
+            working_set.add_decl(Box::new(If));
+            working_set.add_decl(Box::new(To));
+            working_set.add_decl(Box::new(Into));
+            working_set.add_decl(Box::new(Random));
+            working_set.add_decl(Box::new(Split));
+            working_set.add_decl(Box::new(SplitColumn));
+            working_set.add_decl(Box::new(SplitRow));
+            working_set.add_decl(Box::new(Math));
+            working_set.add_decl(Box::new(Path));
+            working_set.add_decl(Box::new(Date));
+            working_set.add_decl(Box::new(Url));
+            working_set.add_decl(Box::new(Ansi));
+            working_set.add_decl(Box::new(Wrap));
+            working_set.add_decl(Box::new(LetEnv));
+            working_set.add_decl(Box::new(Echo));
+            // Adding the command that is being tested to the working set
+            working_set.add_decl(cmd);
+
+            working_set.render()
+        };
+
+        engine_state
+            .merge_delta(delta)
+            .expect("Error merging delta");
+        engine_state
+    }
+
+    fn check_example_input_and_output_types_match_command_signature<'a>(
+        example: &Example,
+        cwd: &PathBuf,
+        engine_state: &mut Box<EngineState>,
+        signature_input_output_types: &Vec<(Type, Type)>,
+        signature_operates_on_cell_paths: bool,
+        signature_vectorizes_over_list: bool,
+    ) -> HashSet<(Type, Type)> {
+        let mut witnessed_type_transformations = HashSet::<(Type, Type)>::new();
+
+        // Skip tests that don't have results to compare to
+        if let Some(example_output) = example.result.as_ref() {
+            if let Some(example_input_type) =
+                eval_pipeline_without_terminal_expression(example.example, &cwd, engine_state)
+            {
+                let example_input_type = example_input_type.get_type();
+                let example_output_type = example_output.get_type();
+
+                let example_matches_signature =
+                    signature_input_output_types
+                        .iter()
+                        .any(|(sig_in_type, sig_out_type)| {
+                            example_input_type.is_subtype(sig_in_type)
+                                && example_output_type.is_subtype(sig_out_type)
+                                && {
+                                    witnessed_type_transformations
+                                        .insert((sig_in_type.clone(), sig_out_type.clone()));
+                                    true
+                                }
+                        });
+
+                // The example type checks as vectorization over an input list if both:
+                // 1. The command is declared to vectorize over list input.
+                // 2. There exists an entry t -> u in the type map such that the
+                //    example_input_type is a subtype of list<t> and the
+                //    example_output_type is a subtype of list<u>.
+                let example_matches_signature_via_vectorization_over_list =
+                    signature_vectorizes_over_list
+                        && match &example_input_type {
+                            Type::List(ex_in_type) => {
+                                match signature_input_output_types.iter().find_map(
+                                    |(sig_in_type, sig_out_type)| {
+                                        if ex_in_type.is_subtype(sig_in_type) {
+                                            Some((sig_in_type, sig_out_type))
+                                        } else {
+                                            None
+                                        }
+                                    },
+                                ) {
+                                    Some((sig_in_type, sig_out_type)) => match &example_output_type
+                                    {
+                                        Type::List(ex_out_type)
+                                            if ex_out_type.is_subtype(sig_out_type) =>
+                                        {
+                                            witnessed_type_transformations.insert((
+                                                sig_in_type.clone(),
+                                                sig_out_type.clone(),
+                                            ));
+                                            true
+                                        }
+                                        _ => false,
+                                    },
+                                    None => false,
+                                }
+                            }
+                            _ => false,
+                        };
+
+                // The example type checks as a cell path operation if both:
+                // 1. The command is declared to operate on cell paths.
+                // 2. The example_input_type is list or record or table, and the example
+                //    output shape is the same as the input shape.
+                let example_matches_signature_via_cell_path_operation =
+                    signature_operates_on_cell_paths
+                        && example_input_type.accepts_cell_paths()
+                        // TODO: This is too permissive; it should make use of the signature.input_output_types at least.
+                        && example_output_type.to_shape() == example_input_type.to_shape();
+
+                if !(example_matches_signature
+                    || example_matches_signature_via_vectorization_over_list
+                    || example_matches_signature_via_cell_path_operation)
+                {
+                    assert!(
+                false,
+                "The example `{}` demonstrates a transformation of type {:?} -> {:?}. \
+                However, this does not match the declared signature: {:?}.{} \
+                For this command, `vectorizes_over_list` is {} and `operates_on_cell_paths()` is {}.",
+                example.example,
+                example_input_type,
+                example_output_type,
+                signature_input_output_types,
+                if signature_input_output_types.is_empty() { " (Did you forget to declare the input and output types for the command?)" } else { "" },
+                signature_vectorizes_over_list,
+                signature_operates_on_cell_paths
+            );
+                };
+            };
+        }
+        witnessed_type_transformations
+    }
+
+    fn check_example_evaluates_to_expected_output(
+        example: &Example,
+        cwd: &PathBuf,
+        engine_state: &mut Box<EngineState>,
+    ) {
         let mut stack = Stack::new();
 
         // Set up PWD
@@ -85,30 +216,82 @@ pub fn test_examples(cmd: impl Command + 'static) {
             .merge_env(&mut stack, &cwd)
             .expect("Error merging environment");
 
-        let (block, delta) = {
-            let mut working_set = StateWorkingSet::new(&*engine_state);
-            let (output, err) = parse(
-                &mut working_set,
-                None,
-                example.example.as_bytes(),
-                false,
-                &[],
+        let empty_input = PipelineData::new(Span::test_data());
+        let result = eval(example.example, empty_input, &cwd, engine_state);
+
+        // Note. Value implements PartialEq for Bool, Int, Float, String and Block
+        // If the command you are testing requires to compare another case, then
+        // you need to define its equality in the Value struct
+        if let Some(expected) = example.result.as_ref() {
+            assert_eq!(
+                &result, expected,
+                "The example result differs from the expected value",
+            )
+        }
+    }
+
+    fn check_all_signature_input_output_types_entries_have_examples(
+        signature: Signature,
+        witnessed_type_transformations: HashSet<(Type, Type)>,
+    ) {
+        let declared_type_transformations =
+            HashSet::from_iter(signature.input_output_types.into_iter());
+        assert!(
+            witnessed_type_transformations.is_subset(&declared_type_transformations),
+            "This should not be possible (bug in test): the type transformations \
+            collected in the course of matching examples to the signature type map \
+            contain type transformations not present in the signature type map."
+        );
+
+        if !signature.allow_variants_without_examples {
+            assert_eq!(
+                witnessed_type_transformations,
+                declared_type_transformations,
+                "There are entries in the signature type map which do not correspond to any example: \
+                {:?}",
+                declared_type_transformations
+                    .difference(&witnessed_type_transformations)
+                    .map(|(s1, s2)| format!("{} -> {}", s1, s2))
+                    .join(", ")
             );
+        }
+    }
 
-            if let Some(err) = err {
-                panic!("test parse error in `{}`: {:?}", example.example, err)
-            }
+    fn eval(
+        contents: &str,
+        input: PipelineData,
+        cwd: &PathBuf,
+        engine_state: &mut Box<EngineState>,
+    ) -> Value {
+        let (block, delta) = parse(contents, engine_state);
+        eval_block(block, input, cwd, engine_state, delta)
+    }
 
-            (output, working_set.render())
-        };
+    fn parse(contents: &str, engine_state: &Box<EngineState>) -> (Block, StateDelta) {
+        let mut working_set = StateWorkingSet::new(&*engine_state);
+        let (output, err) =
+            nu_parser::parse(&mut working_set, None, contents.as_bytes(), false, &[]);
 
+        if let Some(err) = err {
+            panic!("test parse error in `{}`: {:?}", contents, err)
+        }
+
+        (output, working_set.render())
+    }
+
+    fn eval_block(
+        block: Block,
+        input: PipelineData,
+        cwd: &PathBuf,
+        engine_state: &mut Box<EngineState>,
+        delta: StateDelta,
+    ) -> Value {
         engine_state
             .merge_delta(delta)
             .expect("Error merging delta");
 
         let mut stack = Stack::new();
 
-        // Set up PWD
         stack.add_env_var(
             "PWD".to_string(),
             Value::String {
@@ -117,33 +300,34 @@ pub fn test_examples(cmd: impl Command + 'static) {
             },
         );
 
-        match eval_block(
-            &engine_state,
-            &mut stack,
-            &block,
-            PipelineData::new(Span::test_data()),
-            true,
-            true,
-        ) {
-            Err(err) => panic!("test eval error in `{}`: {:?}", example.example, err),
-            Ok(result) => {
-                let result = result.into_value(Span::test_data());
-                println!("input: {}", example.example);
-                println!("result: {:?}", result);
-                println!("done: {:?}", start.elapsed());
+        match nu_engine::eval_block(&engine_state, &mut stack, &block, input, true, true) {
+            Err(err) => panic!("test eval error in `{}`: {:?}", "TODO", err),
+            Ok(result) => result.into_value(Span::test_data()),
+        }
+    }
 
-                // Note. Value implements PartialEq for Bool, Int, Float, String and Block
-                // If the command you are testing requires to compare another case, then
-                // you need to define its equality in the Value struct
-                if let Some(expected) = example.result {
-                    if result != expected {
-                        panic!(
-                            "the example result is different to expected value: {:?} != {:?}",
-                            result, expected
-                        )
-                    }
+    fn eval_pipeline_without_terminal_expression(
+        src: &str,
+        cwd: &PathBuf,
+        engine_state: &mut Box<EngineState>,
+    ) -> Option<Value> {
+        let (mut block, delta) = parse(src, engine_state);
+        match block.pipelines.len() {
+            1 => {
+                let n_expressions = block.pipelines[0].expressions.len();
+                block.pipelines[0].expressions.truncate(&n_expressions - 1);
+
+                if !block.pipelines[0].expressions.is_empty() {
+                    let empty_input = PipelineData::new(Span::test_data());
+                    Some(eval_block(block, empty_input, &cwd, engine_state, delta))
+                } else {
+                    Some(Value::nothing(Span::test_data()))
                 }
             }
+            _ => {
+                // E.g. multiple semicolon-separated statements
+                None
+            }
         }
     }
 }
diff --git a/crates/nu-command/src/filters/all.rs b/crates/nu-command/src/filters/all.rs
index e81c9f938f..f8f2ae6187 100644
--- a/crates/nu-command/src/filters/all.rs
+++ b/crates/nu-command/src/filters/all.rs
@@ -2,7 +2,8 @@ use nu_engine::{eval_block, CallExt};
 use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +16,10 @@ impl Command for All {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::List(Box::new(Type::Any)), Type::Bool),
+                (Type::Table(vec![]), Type::Bool),
+            ])
             .required(
                 "predicate",
                 SyntaxShape::RowCondition,
diff --git a/crates/nu-command/src/filters/any.rs b/crates/nu-command/src/filters/any.rs
index e8de50cff6..335c6597a0 100644
--- a/crates/nu-command/src/filters/any.rs
+++ b/crates/nu-command/src/filters/any.rs
@@ -2,7 +2,8 @@ use nu_engine::{eval_block, CallExt};
 use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +16,10 @@ impl Command for Any {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::List(Box::new(Type::Any)), Type::Bool),
+                (Type::Table(vec![]), Type::Bool),
+            ])
             .required(
                 "predicate",
                 SyntaxShape::RowCondition,
diff --git a/crates/nu-command/src/filters/append.rs b/crates/nu-command/src/filters/append.rs
index bacbfdf50a..6592f67bb4 100644
--- a/crates/nu-command/src/filters/append.rs
+++ b/crates/nu-command/src/filters/append.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,10 @@ impl Command for Append {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("append")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required("row", SyntaxShape::Any, "the row, list, or table to append")
             .category(Category::Filters)
     }
diff --git a/crates/nu-command/src/filters/collect.rs b/crates/nu-command/src/filters/collect.rs
index bd78a34dbb..f994fed717 100644
--- a/crates/nu-command/src/filters/collect.rs
+++ b/crates/nu-command/src/filters/collect.rs
@@ -2,7 +2,7 @@ use nu_engine::{eval_block, redirect_env, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, Signature, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,7 @@ impl Command for Collect {
 
     fn signature(&self) -> Signature {
         Signature::build("collect")
+            .input_output_types(vec![(Type::List(Box::new(Type::Any)), Type::Any)])
             .required(
                 "block",
                 SyntaxShape::Block(Some(vec![SyntaxShape::Any])),
diff --git a/crates/nu-command/src/filters/columns.rs b/crates/nu-command/src/filters/columns.rs
index 840b1e0555..2b96bbd163 100644
--- a/crates/nu-command/src/filters/columns.rs
+++ b/crates/nu-command/src/filters/columns.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, Span, Value,
+    Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,7 +15,12 @@ impl Command for Columns {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build(self.name()).category(Category::Filters)
+        Signature::build(self.name())
+            .input_output_types(vec![(
+                Type::Table(vec![]),
+                Type::List(Box::new(Type::String)),
+            )])
+            .category(Category::Filters)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/filters/compact.rs b/crates/nu-command/src/filters/compact.rs
index 066841b96a..979c418797 100644
--- a/crates/nu-command/src/filters/compact.rs
+++ b/crates/nu-command/src/filters/compact.rs
@@ -1,7 +1,7 @@
 use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call, engine::Command, engine::EngineState, engine::Stack, Category, Example,
-    PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,6 +14,19 @@ impl Command for Compact {
 
     fn signature(&self) -> Signature {
         Signature::build("compact")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    // TODO: Should table be a subtype of List<Any>? If so then this
+                    // entry would be unnecessary.
+                    Type::Table(vec![]),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .rest(
                 "columns",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/filters/default.rs b/crates/nu-command/src/filters/default.rs
index cf02fbc230..1d24f88157 100644
--- a/crates/nu-command/src/filters/default.rs
+++ b/crates/nu-command/src/filters/default.rs
@@ -1,7 +1,9 @@
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, Spanned, SyntaxShape, Value};
+use nu_protocol::{
+    Category, Example, PipelineData, Signature, Span, Spanned, SyntaxShape, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct Default;
@@ -13,6 +15,9 @@ impl Command for Default {
 
     fn signature(&self) -> Signature {
         Signature::build("default")
+            // TODO: Give more specific type signature?
+            // TODO: Declare usage of cell paths in signature? (It seems to behave as if it uses cell paths)
+            .input_output_types(vec![(Type::Any, Type::Any)])
             .required(
                 "default value",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/filters/drop/column.rs b/crates/nu-command/src/filters/drop/column.rs
index 68db655791..0aa3129663 100644
--- a/crates/nu-command/src/filters/drop/column.rs
+++ b/crates/nu-command/src/filters/drop/column.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, CellPath};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, FromValue, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, SyntaxShape, Value,
+    ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,7 @@ impl Command for DropColumn {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .optional(
                 "columns",
                 SyntaxShape::Int,
@@ -25,7 +26,7 @@ impl Command for DropColumn {
     }
 
     fn usage(&self) -> &str {
-        "Remove the last number of columns. If you want to remove columns by name, try 'reject'."
+        "Remove N columns at the right-hand end of the input table. To remove columns by name, use 'reject'."
     }
 
     fn search_terms(&self) -> Vec<&str> {
diff --git a/crates/nu-command/src/filters/drop/drop_.rs b/crates/nu-command/src/filters/drop/drop_.rs
index 863f8b7db8..ce2bb02580 100644
--- a/crates/nu-command/src/filters/drop/drop_.rs
+++ b/crates/nu-command/src/filters/drop/drop_.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,16 +17,19 @@ impl Command for Drop {
 
     fn signature(&self) -> Signature {
         Signature::build("drop")
-            .optional(
-                "rows",
-                SyntaxShape::Int,
-                "starting from the back, the number of rows to remove",
-            )
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
+            .optional("rows", SyntaxShape::Int, "The number of items to remove")
             .category(Category::Filters)
     }
 
     fn usage(&self) -> &str {
-        "Remove the last several rows of the input. Counterpart of 'skip'. Opposite of 'last'."
+        "Remove items/rows from the end of the input list/table. Counterpart of 'skip'. Opposite of 'last'."
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -37,7 +40,7 @@ impl Command for Drop {
         vec![
             Example {
                 example: "[0,1,2,3] | drop",
-                description: "Remove the last item of a list/table",
+                description: "Remove the last item of a list",
                 result: Some(Value::List {
                     vals: vec![Value::test_int(0), Value::test_int(1), Value::test_int(2)],
                     span: Span::test_data(),
@@ -45,7 +48,7 @@ impl Command for Drop {
             },
             Example {
                 example: "[0,1,2,3] | drop 0",
-                description: "Remove zero item of a list/table",
+                description: "Remove zero item of a list",
                 result: Some(Value::List {
                     vals: vec![
                         Value::test_int(0),
@@ -58,12 +61,24 @@ impl Command for Drop {
             },
             Example {
                 example: "[0,1,2,3] | drop 2",
-                description: "Remove the last two items of a list/table",
+                description: "Remove the last two items of a list",
                 result: Some(Value::List {
                     vals: vec![Value::test_int(0), Value::test_int(1)],
                     span: Span::test_data(),
                 }),
             },
+            Example {
+                description: "Remove the last row in a table",
+                example: "[[a, b]; [1, 2] [3, 4]] | drop 1",
+                result: Some(Value::List {
+                    vals: vec![Value::Record {
+                        cols: vec!["a".to_string(), "b".to_string()],
+                        vals: vec![Value::test_int(1), Value::test_int(2)],
+                        span: Span::test_data(),
+                    }],
+                    span: Span::test_data(),
+                }),
+            },
         ]
     }
 
diff --git a/crates/nu-command/src/filters/drop/nth.rs b/crates/nu-command/src/filters/drop/nth.rs
index e3c59b3919..cab0135406 100644
--- a/crates/nu-command/src/filters/drop/nth.rs
+++ b/crates/nu-command/src/filters/drop/nth.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::{Call, RangeInclusion};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, FromValue, IntoInterruptiblePipelineData, PipelineData, PipelineIterator,
-    Range, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Range, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,10 @@ impl Command for DropNth {
 
     fn signature(&self) -> Signature {
         Signature::build("drop nth")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required(
                 "row number or row range",
                 // FIXME: we can make this accept either Int or Range when we can compose SyntaxShapes
diff --git a/crates/nu-command/src/filters/each.rs b/crates/nu-command/src/filters/each.rs
index 42bc53f5e3..f591b4ffaf 100644
--- a/crates/nu-command/src/filters/each.rs
+++ b/crates/nu-command/src/filters/each.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, Signature,
-    Span, SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -35,6 +35,10 @@ with 'transpose' first."#
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("each")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required(
                 "block",
                 SyntaxShape::Block(Some(vec![SyntaxShape::Any])),
diff --git a/crates/nu-command/src/filters/each_while.rs b/crates/nu-command/src/filters/each_while.rs
index f0459cff29..70b7e29cd4 100644
--- a/crates/nu-command/src/filters/each_while.rs
+++ b/crates/nu-command/src/filters/each_while.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, Signature,
-    Span, SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -24,6 +24,10 @@ impl Command for EachWhile {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build(self.name())
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required(
                 "block",
                 SyntaxShape::Block(Some(vec![SyntaxShape::Any])),
diff --git a/crates/nu-command/src/filters/empty.rs b/crates/nu-command/src/filters/empty.rs
index bb4b96efec..3a8840aefd 100644
--- a/crates/nu-command/src/filters/empty.rs
+++ b/crates/nu-command/src/filters/empty.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::{Call, CellPath};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, Signature, Span, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,7 @@ impl Command for Empty {
 
     fn signature(&self) -> Signature {
         Signature::build("is-empty")
+            .input_output_types(vec![(Type::Any, Type::Bool)])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/filters/every.rs b/crates/nu-command/src/filters/every.rs
index 71cf5462c6..5ddd7919ba 100644
--- a/crates/nu-command/src/filters/every.rs
+++ b/crates/nu-command/src/filters/every.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,10 @@ impl Command for Every {
 
     fn signature(&self) -> Signature {
         Signature::build("every")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required(
                 "stride",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/filters/find.rs b/crates/nu-command/src/filters/find.rs
index a2385b5782..80595e56ae 100644
--- a/crates/nu-command/src/filters/find.rs
+++ b/crates/nu-command/src/filters/find.rs
@@ -9,7 +9,7 @@ use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
     Category, Config, Example, IntoInterruptiblePipelineData, ListStream, PipelineData, ShellError,
-    Signature, Span, SyntaxShape, Value,
+    Signature, Span, SyntaxShape, Type, Value,
 };
 use nu_utils::get_ls_colors;
 
@@ -23,6 +23,20 @@ impl Command for Find {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (
+                    // TODO: This is too permissive; if we could express this
+                    // using a type parameter it would be List<T> -> List<T>.
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (Type::String, Type::String),
+                (
+                    // For find -p
+                    Type::Table(vec![]),
+                    Type::Table(vec![]),
+                ),
+            ])
             .named(
                 "predicate",
                 SyntaxShape::Block(Some(vec![SyntaxShape::Any])),
diff --git a/crates/nu-command/src/filters/first.rs b/crates/nu-command/src/filters/first.rs
index fec2f1f584..80430ea1da 100644
--- a/crates/nu-command/src/filters/first.rs
+++ b/crates/nu-command/src/filters/first.rs
@@ -16,6 +16,24 @@ impl Command for First {
 
     fn signature(&self) -> Signature {
         Signature::build("first")
+            .input_output_types(vec![
+                (
+                    // TODO: This variant duplicates the functionality of
+                    // `take`. See #6611, #6611, #6893
+                    // TODO: This is too permissive; if we could express this
+                    // using a type parameter style it would be List<T> ->
+                    // List<T>.
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (
+                    // TODO: This is too permissive; if we could express this
+                    // using a type parameter it would be List<T> -> T.
+                    Type::List(Box::new(Type::Any)),
+                    Type::Any,
+                ),
+                (Type::Binary, Type::Binary),
+            ])
             .optional(
                 "rows",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/filters/flatten.rs b/crates/nu-command/src/filters/flatten.rs
index cdbd9ccd32..a4d8d9e84d 100644
--- a/crates/nu-command/src/filters/flatten.rs
+++ b/crates/nu-command/src/filters/flatten.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::{Call, CellPath, PathMember};
 
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,13 @@ impl Command for Flatten {
 
     fn signature(&self) -> Signature {
         Signature::build("flatten")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (Type::Record(vec![]), Type::Table(vec![])),
+            ])
             .rest(
                 "rest",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/filters/get.rs b/crates/nu-command/src/filters/get.rs
index 42bd3f29e1..f9b8e9a9e0 100644
--- a/crates/nu-command/src/filters/get.rs
+++ b/crates/nu-command/src/filters/get.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, CellPath};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, Signature,
-    SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +20,15 @@ impl Command for Get {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("get")
+            .input_output_types(vec![
+                (
+                    // TODO: This is too permissive; if we could express this
+                    // using a type parameter it would be List<T> -> T.
+                    Type::List(Box::new(Type::Any)),
+                    Type::Any,
+                ),
+                (Type::Table(vec![]), Type::Any),
+            ])
             .required(
                 "cell_path",
                 SyntaxShape::CellPath,
@@ -92,6 +101,24 @@ impl Command for Get {
     }
     fn examples(&self) -> Vec<Example> {
         vec![
+            Example {
+                description: "Get an item from a list",
+                example: "[0 1 2] | get 1",
+                result: Some(Value::test_int(1)),
+            },
+            Example {
+                description: "Get a column from a table",
+                example: "[{A: A0}] | get A",
+                result: Some(Value::List {
+                    vals: vec![Value::test_string("A0")],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Get a cell from a table",
+                example: "[{A: A0}] | get 0.A",
+                result: Some(Value::test_string("A0")),
+            },
             Example {
                 description: "Extract the name of files as a list",
                 example: "ls | get name",
@@ -125,3 +152,15 @@ impl Command for Get {
         ]
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(Get)
+    }
+}
diff --git a/crates/nu-command/src/filters/group.rs b/crates/nu-command/src/filters/group.rs
index 414d26ffe2..62869b073d 100644
--- a/crates/nu-command/src/filters/group.rs
+++ b/crates/nu-command/src/filters/group.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,14 @@ impl Command for Group {
 
     fn signature(&self) -> Signature {
         Signature::build("group")
+            // TODO: It accepts Table also, but currently there is no Table
+            // example. Perhaps Table should be a subtype of List, in which case
+            // the current signature would suffice even when a Table example
+            // exists.
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::List(Box::new(Type::Any)))),
+            )])
             .required("group_size", SyntaxShape::Int, "the size of each group")
             .category(Category::Filters)
     }
diff --git a/crates/nu-command/src/filters/group_by.rs b/crates/nu-command/src/filters/group_by.rs
index 7e938329e6..49d2364a0d 100644
--- a/crates/nu-command/src/filters/group_by.rs
+++ b/crates/nu-command/src/filters/group_by.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 use indexmap::IndexMap;
@@ -17,15 +17,20 @@ impl Command for GroupBy {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("group-by").optional(
-            "grouper",
-            SyntaxShape::Any,
-            "the grouper value to use",
-        )
+        Signature::build("group-by")
+            // TODO: It accepts Table also, but currently there is no Table
+            // example. Perhaps Table should be a subtype of List, in which case
+            // the current signature would suffice even when a Table example
+            // exists.
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::Record(vec![]),
+            )])
+            .optional("grouper", SyntaxShape::Any, "the grouper value to use")
     }
 
     fn usage(&self) -> &str {
-        "Split a table into groups based on one column's values, and return a record with those groups."
+        "Splits a list or table into groups, and returns a record containing those groups."
     }
 
     fn run(
@@ -47,7 +52,7 @@ impl Command for GroupBy {
             },
             Example {
                 description: "You can also group by raw values by leaving out the argument",
-                example: "echo ['1' '3' '1' '3' '2' '1' '1'] | group-by",
+                example: "['1' '3' '1' '3' '2' '1' '1'] | group-by",
                 result: Some(Value::Record {
                     cols: vec!["1".to_string(), "3".to_string(), "2".to_string()],
                     vals: vec![
diff --git a/crates/nu-command/src/filters/headers.rs b/crates/nu-command/src/filters/headers.rs
index aeb9f61d99..50b318402a 100644
--- a/crates/nu-command/src/filters/headers.rs
+++ b/crates/nu-command/src/filters/headers.rs
@@ -1,7 +1,8 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -13,7 +14,16 @@ impl Command for Headers {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build(self.name()).category(Category::Filters)
+        Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    // Tables with missing values are List<Any>
+                    Type::List(Box::new(Type::Any)),
+                    Type::Table(vec![]),
+                ),
+            ])
+            .category(Category::Filters)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/filters/insert.rs b/crates/nu-command/src/filters/insert.rs
index b3c1c46c4b..8682d51862 100644
--- a/crates/nu-command/src/filters/insert.rs
+++ b/crates/nu-command/src/filters/insert.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, CellPath, PathMember};
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, FromValue, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, SyntaxShape, Value,
+    ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,14 @@ impl Command for Insert {
 
     fn signature(&self) -> Signature {
         Signature::build("insert")
+            .input_output_types(vec![
+                (Type::Record(vec![]), Type::Record(vec![])),
+                // TODO: It accepts table input also (in which case it repeats
+                // the value across all table rows) but currently there is no
+                // example of the table variant so it cannot be in the
+                // signature.
+                // (Type::Table(vec![]), Type::Table(vec![])),
+            ])
             .required(
                 "field",
                 SyntaxShape::CellPath,
@@ -49,8 +57,8 @@ impl Command for Insert {
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Insert a new value",
-            example: "echo {'name': 'nu', 'stars': 5} | insert alias 'Nushell'",
+            description: "Insert a new entry into a record",
+            example: "{'name': 'nu', 'stars': 5} | insert alias 'Nushell'",
             result: Some(Value::Record {
                 cols: vec!["name".into(), "stars".into(), "alias".into()],
                 vals: vec![
diff --git a/crates/nu-command/src/filters/last.rs b/crates/nu-command/src/filters/last.rs
index 09e55ce3fa..f960769316 100644
--- a/crates/nu-command/src/filters/last.rs
+++ b/crates/nu-command/src/filters/last.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, Span, SyntaxShape, Value,
+    Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,23 @@ impl Command for Last {
 
     fn signature(&self) -> Signature {
         Signature::build("last")
+            .input_output_types(vec![
+                (
+                    // TODO: This variant duplicates the functionality of
+                    // `take`. See #6611, #6611, #6893
+                    // TODO: This is too permissive; if we could express this
+                    // using a type parameter style it would be List<T> ->
+                    // List<T>.
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (
+                    // TODO: This is too permissive; if we could express this
+                    // using a type parameter it would be List<T> -> T.
+                    Type::List(Box::new(Type::Any)),
+                    Type::Any,
+                ),
+            ])
             .optional(
                 "rows",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/filters/length.rs b/crates/nu-command/src/filters/length.rs
index eb41b145fc..9ad4e62829 100644
--- a/crates/nu-command/src/filters/length.rs
+++ b/crates/nu-command/src/filters/length.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, Span, Value,
+    Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +20,10 @@ impl Command for Length {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("length")
+            .input_output_types(vec![
+                (Type::List(Box::new(Type::Any)), Type::Int),
+                (Type::Table(vec![]), Type::Int),
+            ])
             .switch("column", "Show the number of columns in a table", Some('c'))
             .category(Category::Filters)
     }
diff --git a/crates/nu-command/src/filters/lines.rs b/crates/nu-command/src/filters/lines.rs
index dcc47806a2..02b4e8c6cc 100644
--- a/crates/nu-command/src/filters/lines.rs
+++ b/crates/nu-command/src/filters/lines.rs
@@ -2,7 +2,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, RawStream, ShellError,
-    Signature, Span, Value,
+    Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,7 @@ impl Command for Lines {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("lines")
+            .input_output_types(vec![(Type::String, Type::List(Box::new(Type::String)))])
             .switch("skip-empty", "skip empty lines", Some('s'))
             .category(Category::Filters)
     }
diff --git a/crates/nu-command/src/filters/merge.rs b/crates/nu-command/src/filters/merge.rs
index 2a9f306f27..b047d5e48a 100644
--- a/crates/nu-command/src/filters/merge.rs
+++ b/crates/nu-command/src/filters/merge.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, FromValue, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, SyntaxShape, Value,
+    ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -29,6 +29,10 @@ repeating this process with row 1, and so on."#
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("merge")
+            .input_output_types(vec![
+                (Type::Record(vec![]), Type::Record(vec![])),
+                (Type::Table(vec![]), Type::Table(vec![])),
+            ])
             .required(
                 "block",
                 // Both this and `update` should have a shape more like <record> | <table> | <block> than just <any>. -Leon 2022-10-27
@@ -64,10 +68,11 @@ repeating this process with row 1, and so on."#
             Example {
                 example: "{a: 1, b: 2} | merge {c: 3}",
                 description: "Merge two records",
-                result: Some(Value::test_record(
-                    vec!["a", "b", "c"],
-                    vec![Value::test_int(1), Value::test_int(2), Value::test_int(3)],
-                )),
+                result: Some(Value::Record {
+                    cols: vec!["a".to_string(), "b".to_string(), "c".to_string()],
+                    vals: vec![Value::test_int(1), Value::test_int(2), Value::test_int(3)],
+                    span: Span::test_data(),
+                }),
             },
             Example {
                 example: "{a: 1, b: 3} | merge { { b: 2 } | merge { c: 4 } }",
@@ -77,6 +82,17 @@ repeating this process with row 1, and so on."#
                     vec![Value::test_int(1), Value::test_int(2), Value::test_int(4)],
                 )),
             },
+            Example {
+                example: "[{columnA: A0 columnB: B0}] | merge [{columnA: 'A0*'}]",
+                description: "Merge two tables, overwriting overlapping columns",
+                result: Some(Value::List {
+                    vals: vec![Value::test_record(
+                        vec!["columnA", "columnB"],
+                        vec![Value::test_string("A0*"), Value::test_string("B0")],
+                    )],
+                    span: Span::test_data(),
+                }),
+            },
         ]
     }
 
diff --git a/crates/nu-command/src/filters/move_.rs b/crates/nu-command/src/filters/move_.rs
index 25490ee5eb..52eb6a5798 100644
--- a/crates/nu-command/src/filters/move_.rs
+++ b/crates/nu-command/src/filters/move_.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, Span, Spanned, SyntaxShape, Value,
+    Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone, Debug)]
@@ -26,6 +26,10 @@ impl Command for Move {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("move")
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (Type::Record(vec![]), Type::Record(vec![])),
+            ])
             .rest("columns", SyntaxShape::String, "the columns to move")
             .named(
                 "after",
diff --git a/crates/nu-command/src/filters/par_each.rs b/crates/nu-command/src/filters/par_each.rs
index d1d2572753..fc1f4ea736 100644
--- a/crates/nu-command/src/filters/par_each.rs
+++ b/crates/nu-command/src/filters/par_each.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, Signature,
-    Span, SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 use rayon::prelude::*;
 
@@ -23,6 +23,10 @@ impl Command for ParEach {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("par-each")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required(
                 "block",
                 SyntaxShape::Block(Some(vec![SyntaxShape::Any])),
diff --git a/crates/nu-command/src/filters/prepend.rs b/crates/nu-command/src/filters/prepend.rs
index d9b56c9555..ea3699b9fd 100644
--- a/crates/nu-command/src/filters/prepend.rs
+++ b/crates/nu-command/src/filters/prepend.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,10 @@ impl Command for Prepend {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("prepend")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required(
                 "row",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/filters/range.rs b/crates/nu-command/src/filters/range.rs
index e2169fb660..431ceca31e 100644
--- a/crates/nu-command/src/filters/range.rs
+++ b/crates/nu-command/src/filters/range.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::{Call, RangeInclusion};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,10 @@ impl Command for Range {
 
     fn signature(&self) -> Signature {
         Signature::build("range")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
             .required(
                 "rows",
                 SyntaxShape::Range,
diff --git a/crates/nu-command/src/filters/reduce.rs b/crates/nu-command/src/filters/reduce.rs
index 902f3ff7f7..8eef1e9936 100644
--- a/crates/nu-command/src/filters/reduce.rs
+++ b/crates/nu-command/src/filters/reduce.rs
@@ -5,7 +5,7 @@ use nu_engine::{eval_block, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
-    Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -18,6 +18,7 @@ impl Command for Reduce {
 
     fn signature(&self) -> Signature {
         Signature::build("reduce")
+            .input_output_types(vec![(Type::List(Box::new(Type::Any)), Type::Any)])
             .named(
                 "fold",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/filters/reject.rs b/crates/nu-command/src/filters/reject.rs
index a7029638c0..9481a83d0a 100644
--- a/crates/nu-command/src/filters/reject.rs
+++ b/crates/nu-command/src/filters/reject.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, CellPath};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,10 @@ impl Command for Reject {
 
     fn signature(&self) -> Signature {
         Signature::build("reject")
+            .input_output_types(vec![
+                (Type::Record(vec![]), Type::Record(vec![])),
+                (Type::Table(vec![]), Type::Table(vec![])),
+            ])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
@@ -25,7 +29,7 @@ impl Command for Reject {
     }
 
     fn usage(&self) -> &str {
-        "Remove the given columns from the table. If you want to remove rows, try 'drop'."
+        "Remove the given columns from the table. To remove rows, use 'drop'."
     }
 
     fn run(
@@ -43,13 +47,25 @@ impl Command for Reject {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Lists the files in a directory without showing the modified column",
+                description: "Reject a column in the `ls` table",
                 example: "ls | reject modified",
                 result: None,
             },
+            Example {
+                description: "Reject a column in a table",
+                example: "[[a, b]; [1, 2]] | reject a",
+                result: Some(Value::List {
+                    vals: vec![Value::Record {
+                        cols: vec!["b".to_string()],
+                        vals: vec![Value::test_int(2)],
+                        span: Span::test_data(),
+                    }],
+                    span: Span::test_data(),
+                }),
+            },
             Example {
                 description: "Reject the specified field in a record",
-                example: "echo {a: 1, b: 2} | reject a",
+                example: "{a: 1, b: 2} | reject a",
                 result: Some(Value::Record {
                     cols: vec!["b".into()],
                     vals: vec![Value::Int {
@@ -61,7 +77,7 @@ impl Command for Reject {
             },
             Example {
                 description: "Reject a nested field in a record",
-                example: "echo {a: {b: 3,c: 5}} | reject a.b",
+                example: "{a: {b: 3, c: 5}} | reject a.b",
                 result: Some(Value::Record {
                     cols: vec!["a".into()],
                     vals: vec![Value::Record {
diff --git a/crates/nu-command/src/filters/rename.rs b/crates/nu-command/src/filters/rename.rs
index 32fa9b3680..4c90f6ccea 100644
--- a/crates/nu-command/src/filters/rename.rs
+++ b/crates/nu-command/src/filters/rename.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,10 @@ impl Command for Rename {
 
     fn signature(&self) -> Signature {
         Signature::build("rename")
+            .input_output_types(vec![
+                (Type::Record(vec![]), Type::Record(vec![])),
+                (Type::Table(vec![]), Type::Table(vec![])),
+            ])
             .named(
                 "column",
                 SyntaxShape::List(Box::new(SyntaxShape::String)),
@@ -77,6 +81,15 @@ impl Command for Rename {
                     span: Span::test_data(),
                 }),
             },
+            Example {
+                description: "Rename the fields of a record",
+                example: "{a: 1 b: 2} | rename x y",
+                result: Some(Value::Record {
+                    cols: vec!["x".to_string(), "y".to_string()],
+                    vals: vec![Value::test_int(1), Value::test_int(2)],
+                    span: Span::test_data(),
+                }),
+            },
         ]
     }
 }
diff --git a/crates/nu-command/src/filters/reverse.rs b/crates/nu-command/src/filters/reverse.rs
index 566871ccd5..c21439918c 100644
--- a/crates/nu-command/src/filters/reverse.rs
+++ b/crates/nu-command/src/filters/reverse.rs
@@ -2,7 +2,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,11 +14,19 @@ impl Command for Reverse {
     }
 
     fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("reverse").category(Category::Filters)
+        Signature::build("reverse")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (Type::Table(vec![]), Type::Table(vec![])),
+            ])
+            .category(Category::Filters)
     }
 
     fn usage(&self) -> &str {
-        "Reverses the table."
+        "Reverses the input list or table."
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -26,19 +34,32 @@ impl Command for Reverse {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            example: "[0,1,2,3] | reverse",
-            description: "Reverse the items",
-            result: Some(Value::List {
-                vals: vec![
-                    Value::test_int(3),
-                    Value::test_int(2),
-                    Value::test_int(1),
-                    Value::test_int(0),
-                ],
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                example: "[0,1,2,3] | reverse",
+                description: "Reverse a list",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::test_int(3),
+                        Value::test_int(2),
+                        Value::test_int(1),
+                        Value::test_int(0),
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                example: "[{a: 1} {a: 2}] | reverse",
+                description: "Reverse a table",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::test_record(vec!["a"], vec![Value::test_int(2)]),
+                        Value::test_record(vec!["a"], vec![Value::test_int(1)]),
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 
     fn run(
diff --git a/crates/nu-command/src/filters/roll/roll_down.rs b/crates/nu-command/src/filters/roll/roll_down.rs
index 4207471188..770108d838 100644
--- a/crates/nu-command/src/filters/roll/roll_down.rs
+++ b/crates/nu-command/src/filters/roll/roll_down.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 use super::{vertical_rotate_value, VerticalDirection};
@@ -22,6 +22,8 @@ impl Command for RollDown {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            // TODO: It also operates on List
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .named("by", SyntaxShape::Int, "Number of rows to roll", Some('b'))
             .category(Category::Filters)
     }
@@ -33,7 +35,7 @@ impl Command for RollDown {
     fn examples(&self) -> Vec<Example> {
         let columns = vec!["a".to_string(), "b".to_string()];
         vec![Example {
-            description: "Rolls rows down",
+            description: "Rolls rows down of a table",
             example: "[[a b]; [1 2] [3 4] [5 6]] | roll down",
             result: Some(Value::List {
                 vals: vec![
diff --git a/crates/nu-command/src/filters/roll/roll_left.rs b/crates/nu-command/src/filters/roll/roll_left.rs
index 19c0957b6c..28422745d6 100644
--- a/crates/nu-command/src/filters/roll/roll_left.rs
+++ b/crates/nu-command/src/filters/roll/roll_left.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 use super::{horizontal_rotate_value, HorizontalDirection};
@@ -22,6 +22,7 @@ impl Command for RollLeft {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .named(
                 "by",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/filters/roll/roll_right.rs b/crates/nu-command/src/filters/roll/roll_right.rs
index e6759e725e..c1554302db 100644
--- a/crates/nu-command/src/filters/roll/roll_right.rs
+++ b/crates/nu-command/src/filters/roll/roll_right.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 use super::{horizontal_rotate_value, HorizontalDirection};
@@ -22,6 +22,7 @@ impl Command for RollRight {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .named(
                 "by",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/filters/roll/roll_up.rs b/crates/nu-command/src/filters/roll/roll_up.rs
index 38b843fe00..5d136d1547 100644
--- a/crates/nu-command/src/filters/roll/roll_up.rs
+++ b/crates/nu-command/src/filters/roll/roll_up.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 use super::{vertical_rotate_value, VerticalDirection};
@@ -22,6 +22,8 @@ impl Command for RollUp {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            // TODO: It also operates on List
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .named("by", SyntaxShape::Int, "Number of rows to roll", Some('b'))
             .category(Category::Filters)
     }
diff --git a/crates/nu-command/src/filters/rotate.rs b/crates/nu-command/src/filters/rotate.rs
index 2d4cced010..a500e28db6 100644
--- a/crates/nu-command/src/filters/rotate.rs
+++ b/crates/nu-command/src/filters/rotate.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,7 @@ impl Command for Rotate {
 
     fn signature(&self) -> Signature {
         Signature::build("rotate")
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .switch("ccw", "rotate counter clockwise", None)
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/filters/select.rs b/crates/nu-command/src/filters/select.rs
index 05c40a45df..927e3de74b 100644
--- a/crates/nu-command/src/filters/select.rs
+++ b/crates/nu-command/src/filters/select.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, CellPath, PathMember};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    PipelineIterator, ShellError, Signature, Span, SyntaxShape, Value,
+    PipelineIterator, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,10 @@ impl Command for Select {
     // FIXME: also add support for --skip
     fn signature(&self) -> Signature {
         Signature::build("select")
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (Type::Record(vec![]), Type::Record(vec![])),
+            ])
             .switch(
                 "ignore-errors",
                 "when a column has empty cells, instead of erroring out, replace them with nothing",
@@ -54,6 +58,19 @@ impl Command for Select {
 
     fn examples(&self) -> Vec<Example> {
         vec![
+            Example {
+                description: "Select a column in a table",
+                example: "[{a: a b: b}] | select a",
+                result: Some(Value::List {
+                    vals: vec![Value::test_record(vec!["a"], vec![Value::test_string("a")])],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Select a field in a record",
+                example: "{a: a b: b} | select a",
+                result: Some(Value::test_record(vec!["a"], vec![Value::test_string("a")])),
+            },
             Example {
                 description: "Select just the name column",
                 example: "ls | select name",
@@ -259,3 +276,15 @@ impl Iterator for NthIterator {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(Select)
+    }
+}
diff --git a/crates/nu-command/src/filters/shuffle.rs b/crates/nu-command/src/filters/shuffle.rs
index 47e23d722d..81bbd70cf1 100644
--- a/crates/nu-command/src/filters/shuffle.rs
+++ b/crates/nu-command/src/filters/shuffle.rs
@@ -1,7 +1,7 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature,
+    Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Type,
 };
 use rand::prelude::SliceRandom;
 use rand::thread_rng;
@@ -15,7 +15,12 @@ impl Command for Shuffle {
     }
 
     fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("shuffle").category(Category::Filters)
+        Signature::build("shuffle")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::Any)),
+            )])
+            .category(Category::Filters)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/filters/skip/skip_.rs b/crates/nu-command/src/filters/skip/skip_.rs
index c1c2c03154..cd7ebf28a1 100644
--- a/crates/nu-command/src/filters/skip/skip_.rs
+++ b/crates/nu-command/src/filters/skip/skip_.rs
@@ -5,7 +5,7 @@ use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, Span, SyntaxShape, Value,
+    Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -18,6 +18,13 @@ impl Command for Skip {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .optional("n", SyntaxShape::Int, "the number of elements to skip")
             .category(Category::Filters)
     }
@@ -31,13 +38,21 @@ impl Command for Skip {
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["ignore", "remove"]
+        vec!["ignore", "remove", "last", "slice", "tail"]
     }
 
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Skip two elements",
+                description: "Skip the first value of a list",
+                example: "echo [2 4 6 8] | skip 1",
+                result: Some(Value::List {
+                    vals: vec![Value::test_int(4), Value::test_int(6), Value::test_int(8)],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Skip two rows of a table",
                 example: "echo [[editions]; [2015] [2018] [2021]] | skip 2",
                 result: Some(Value::List {
                     vals: vec![Value::Record {
@@ -48,14 +63,6 @@ impl Command for Skip {
                     span: Span::test_data(),
                 }),
             },
-            Example {
-                description: "Skip the first value",
-                example: "echo [2 4 6 8] | skip",
-                result: Some(Value::List {
-                    vals: vec![Value::test_int(4), Value::test_int(6), Value::test_int(8)],
-                    span: Span::test_data(),
-                }),
-            },
         ]
     }
 
diff --git a/crates/nu-command/src/filters/skip/skip_until.rs b/crates/nu-command/src/filters/skip/skip_until.rs
index 75afa69b80..0d0dbfb494 100644
--- a/crates/nu-command/src/filters/skip/skip_until.rs
+++ b/crates/nu-command/src/filters/skip/skip_until.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,13 @@ impl Command for SkipUntil {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .required(
                 "predicate",
                 SyntaxShape::RowCondition,
@@ -33,14 +40,27 @@ impl Command for SkipUntil {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Skip until the element is positive",
-            example: "echo [-2 0 2 -1] | skip until $it > 0",
-            result: Some(Value::List {
-                vals: vec![Value::test_int(2), Value::test_int(-1)],
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                description: "Skip until the element is positive",
+                example: "[-2 0 2 -1] | skip until $it > 0",
+                result: Some(Value::List {
+                    vals: vec![Value::test_int(2), Value::test_int(-1)],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Skip until the field value is positive",
+                example: "[{a: -2} {a: 0} {a: 2} {a: -1}] | skip until $it.a > 0",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::test_record(vec!["a"], vec![Value::test_int(2)]),
+                        Value::test_record(vec!["a"], vec![Value::test_int(-1)]),
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 
     fn run(
diff --git a/crates/nu-command/src/filters/skip/skip_while.rs b/crates/nu-command/src/filters/skip/skip_while.rs
index e43b5c2edf..2ce137d2de 100644
--- a/crates/nu-command/src/filters/skip/skip_while.rs
+++ b/crates/nu-command/src/filters/skip/skip_while.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,13 @@ impl Command for SkipWhile {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .required(
                 "predicate",
                 SyntaxShape::RowCondition,
@@ -33,14 +40,28 @@ impl Command for SkipWhile {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Skip while the element is negative",
-            example: "echo [-2 0 2 -1] | skip while $it < 0",
-            result: Some(Value::List {
-                vals: vec![Value::test_int(0), Value::test_int(2), Value::test_int(-1)],
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                description: "Skip while the element is negative",
+                example: "[-2 0 2 -1] | skip while $it < 0",
+                result: Some(Value::List {
+                    vals: vec![Value::test_int(0), Value::test_int(2), Value::test_int(-1)],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Skip while the field value is negative",
+                example: "[{a: -2} {a: 0} {a: 2} {a: -1}] | skip while $it.a < 0",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::test_record(vec!["a"], vec![Value::test_int(0)]),
+                        Value::test_record(vec!["a"], vec![Value::test_int(2)]),
+                        Value::test_record(vec!["a"], vec![Value::test_int(-1)]),
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 
     fn run(
diff --git a/crates/nu-command/src/filters/sort.rs b/crates/nu-command/src/filters/sort.rs
index 065c3c33ab..a7a982df12 100644
--- a/crates/nu-command/src/filters/sort.rs
+++ b/crates/nu-command/src/filters/sort.rs
@@ -2,7 +2,7 @@ use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, Span, Value,
+    Signature, Span, Type, Value,
 };
 use std::cmp::Ordering;
 
@@ -16,7 +16,11 @@ impl Command for Sort {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("sort")
-            .switch("reverse", "Sort in reverse order", Some('r'))
+        .input_output_types(vec![(
+            Type::List(Box::new(Type::Any)),
+            Type::List(Box::new(Type::Any)),
+        ), (Type::Record(vec![]), Type::Record(vec![])),])
+    .switch("reverse", "Sort in reverse order", Some('r'))
             .switch(
                 "insensitive",
                 "Sort string-based columns case-insensitively",
diff --git a/crates/nu-command/src/filters/sort_by.rs b/crates/nu-command/src/filters/sort_by.rs
index 35c20511f6..aa3f4f3976 100644
--- a/crates/nu-command/src/filters/sort_by.rs
+++ b/crates/nu-command/src/filters/sort_by.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,13 @@ impl Command for SortBy {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("sort-by")
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .rest("columns", SyntaxShape::Any, "the column(s) to sort by")
             .switch("reverse", "Sort in reverse order", Some('r'))
             .switch(
diff --git a/crates/nu-command/src/filters/split_by.rs b/crates/nu-command/src/filters/split_by.rs
index 25c164079f..93b328feb3 100644
--- a/crates/nu-command/src/filters/split_by.rs
+++ b/crates/nu-command/src/filters/split_by.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,11 +14,9 @@ impl Command for SplitBy {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("split-by").optional(
-            "splitter",
-            SyntaxShape::Any,
-            "the splitter value to use",
-        )
+        Signature::build("split-by")
+            .input_output_types(vec![(Type::Record(vec![]), Type::Record(vec![]))])
+            .optional("splitter", SyntaxShape::Any, "the splitter value to use")
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/filters/take/take_.rs b/crates/nu-command/src/filters/take/take_.rs
index a99d651ca2..356c42675b 100644
--- a/crates/nu-command/src/filters/take/take_.rs
+++ b/crates/nu-command/src/filters/take/take_.rs
@@ -16,6 +16,13 @@ impl Command for Take {
 
     fn signature(&self) -> Signature {
         Signature::build("take")
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .required(
                 "n",
                 SyntaxShape::Int,
@@ -28,6 +35,10 @@ impl Command for Take {
         "Take only the first n elements."
     }
 
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["first", "slice", "head"]
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,
@@ -56,6 +67,17 @@ impl Command for Take {
                     span: Span::test_data(),
                 }),
             },
+            Example {
+                description: "Return the first two rows of a table",
+                example: "echo [[editions]; [2015] [2018] [2021]] | take 2",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::test_record(vec!["editions"], vec![Value::test_int(2015)]),
+                        Value::test_record(vec!["editions"], vec![Value::test_int(2018)]),
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
         ]
     }
 }
diff --git a/crates/nu-command/src/filters/take/take_until.rs b/crates/nu-command/src/filters/take/take_until.rs
index bddc251c32..9a1c4c0188 100644
--- a/crates/nu-command/src/filters/take/take_until.rs
+++ b/crates/nu-command/src/filters/take/take_until.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,13 @@ impl Command for TakeUntil {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .required(
                 "predicate",
                 SyntaxShape::RowCondition,
@@ -29,14 +36,27 @@ impl Command for TakeUntil {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Take until the element is positive",
-            example: "echo [-1 -2 9 1] | take until $it > 0",
-            result: Some(Value::List {
-                vals: vec![Value::test_int(-1), Value::test_int(-2)],
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                description: "Take until the element is positive",
+                example: "[-1 -2 9 1] | take until $it > 0",
+                result: Some(Value::List {
+                    vals: vec![Value::test_int(-1), Value::test_int(-2)],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Take until the field value is positive",
+                example: "[{a: -1} {a: -2} {a: 9} {a: 1}] | take until $it.a > 0",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::test_record(vec!["a"], vec![Value::test_int(-1)]),
+                        Value::test_record(vec!["a"], vec![Value::test_int(-2)]),
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 
     fn run(
diff --git a/crates/nu-command/src/filters/take/take_while.rs b/crates/nu-command/src/filters/take/take_while.rs
index 67c7aa3835..6b43709025 100644
--- a/crates/nu-command/src/filters/take/take_while.rs
+++ b/crates/nu-command/src/filters/take/take_while.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{CaptureBlock, Command, EngineState, Stack},
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,13 @@ impl Command for TakeWhile {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+            ])
             .required(
                 "predicate",
                 SyntaxShape::RowCondition,
@@ -29,14 +36,27 @@ impl Command for TakeWhile {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Take while the element is negative",
-            example: "echo [-1 -2 9 1] | take while $it < 0",
-            result: Some(Value::List {
-                vals: vec![Value::test_int(-1), Value::test_int(-2)],
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                description: "Take while the element is negative",
+                example: "[-1 -2 9 1] | take while $it < 0",
+                result: Some(Value::List {
+                    vals: vec![Value::test_int(-1), Value::test_int(-2)],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Take while the field value is negative",
+                example: "[{a: -1} {a: -2} {a: 9} {a: 1}] | take while $it.a < 0",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::test_record(vec!["a"], vec![Value::test_int(-1)]),
+                        Value::test_record(vec!["a"], vec![Value::test_int(-2)]),
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 
     fn run(
diff --git a/crates/nu-command/src/filters/transpose.rs b/crates/nu-command/src/filters/transpose.rs
index 0a3761466b..2ec7166fa6 100644
--- a/crates/nu-command/src/filters/transpose.rs
+++ b/crates/nu-command/src/filters/transpose.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -26,6 +26,10 @@ impl Command for Transpose {
 
     fn signature(&self) -> Signature {
         Signature::build("transpose")
+            .input_output_types(vec![
+                (Type::Table(vec![]), Type::Table(vec![])),
+                (Type::Table(vec![]), Type::Record(vec![])),
+            ])
             .switch(
                 "header-row",
                 "treat the first row as column names",
@@ -81,7 +85,7 @@ impl Command for Transpose {
         vec![
             Example {
                 description: "Transposes the table contents with default column names",
-                example: "echo [[c1 c2]; [1 2]] | transpose",
+                example: "[[c1 c2]; [1 2]] | transpose",
                 result: Some(Value::List {
                     vals: vec![
                         Value::Record {
@@ -100,7 +104,7 @@ impl Command for Transpose {
             },
             Example {
                 description: "Transposes the table contents with specified column names",
-                example: "echo [[c1 c2]; [1 2]] | transpose key val",
+                example: "[[c1 c2]; [1 2]] | transpose key val",
                 result: Some(Value::List {
                     vals: vec![
                         Value::Record {
@@ -120,7 +124,7 @@ impl Command for Transpose {
             Example {
                 description:
                     "Transposes the table without column names and specify a new column name",
-                example: "echo [[c1 c2]; [1 2]] | transpose -i val",
+                example: "[[c1 c2]; [1 2]] | transpose -i val",
                 result: Some(Value::List {
                     vals: vec![
                         Value::Record {
@@ -139,7 +143,7 @@ impl Command for Transpose {
             },
             Example {
                 description: "Transfer back to record with -d flag",
-                example: "echo {c1: 1, c2: 2} | transpose | transpose -i -r -d",
+                example: "{c1: 1, c2: 2} | transpose | transpose -i -r -d",
                 result: Some(Value::Record {
                     cols: vec!["c1".to_string(), "c2".to_string()],
                     vals: vec![Value::test_int(1), Value::test_int(2)],
diff --git a/crates/nu-command/src/filters/uniq.rs b/crates/nu-command/src/filters/uniq.rs
index f64e3b7f3b..30ff0963d3 100644
--- a/crates/nu-command/src/filters/uniq.rs
+++ b/crates/nu-command/src/filters/uniq.rs
@@ -2,7 +2,9 @@ use std::collections::VecDeque;
 
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, IntoPipelineData, PipelineData, Signature, Span, Value};
+use nu_protocol::{
+    Category, Example, IntoPipelineData, PipelineData, Signature, Span, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct Uniq;
@@ -14,6 +16,17 @@ impl Command for Uniq {
 
     fn signature(&self) -> Signature {
         Signature::build("uniq")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (
+                    // -c
+                    Type::List(Box::new(Type::Any)),
+                    Type::Table(vec![]),
+                ),
+            ])
             .switch(
                 "count",
                 "Return a table containing the distinct input values together with their counts",
diff --git a/crates/nu-command/src/filters/update.rs b/crates/nu-command/src/filters/update.rs
index 5087e68f3d..027eb65bd3 100644
--- a/crates/nu-command/src/filters/update.rs
+++ b/crates/nu-command/src/filters/update.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, CellPath, PathMember};
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, FromValue, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, SyntaxShape, Value,
+    ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,7 @@ impl Command for Update {
 
     fn signature(&self) -> Signature {
         Signature::build("update")
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .required(
                 "field",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/filters/update_cells.rs b/crates/nu-command/src/filters/update_cells.rs
index 6dc33b6b9d..4fc8e8d6df 100644
--- a/crates/nu-command/src/filters/update_cells.rs
+++ b/crates/nu-command/src/filters/update_cells.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Block, Call};
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    PipelineIterator, ShellError, Signature, Span, SyntaxShape, Value,
+    PipelineIterator, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 use std::collections::HashSet;
 use std::iter::FromIterator;
@@ -18,6 +18,7 @@ impl Command for UpdateCells {
 
     fn signature(&self) -> Signature {
         Signature::build("update cells")
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .required(
                 "block",
                 SyntaxShape::Block(Some(vec![SyntaxShape::Any])),
diff --git a/crates/nu-command/src/filters/upsert.rs b/crates/nu-command/src/filters/upsert.rs
index 4472177f58..ac85701569 100644
--- a/crates/nu-command/src/filters/upsert.rs
+++ b/crates/nu-command/src/filters/upsert.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::{Call, CellPath, PathMember};
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, FromValue, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, SyntaxShape, Value,
+    ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,7 @@ impl Command for Upsert {
 
     fn signature(&self) -> Signature {
         Signature::build("upsert")
+            .input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
             .required(
                 "field",
                 SyntaxShape::CellPath,
@@ -50,19 +51,19 @@ impl Command for Upsert {
     fn examples(&self) -> Vec<Example> {
         vec![Example {
             description: "Update a column value",
-            example: "echo {'name': 'nu', 'stars': 5} | upsert name 'Nushell'",
+            example: "{'name': 'nu', 'stars': 5} | upsert name 'Nushell'",
             result: Some(Value::Record { cols: vec!["name".into(), "stars".into()], vals: vec![Value::test_string("Nushell"), Value::test_int(5)], span: Span::test_data()}),
         }, Example {
             description: "Insert a new column",
-            example: "echo {'name': 'nu', 'stars': 5} | upsert language 'Rust'",
+            example: "{'name': 'nu', 'stars': 5} | upsert language 'Rust'",
             result: Some(Value::Record { cols: vec!["name".into(), "stars".into(), "language".into()], vals: vec![Value::test_string("nu"), Value::test_int(5), Value::test_string("Rust")], span: Span::test_data()}),
         }, Example {
             description: "Use in block form for more involved updating logic",
-            example: "echo [[count fruit]; [1 'apple']] | upsert count {|f| $f.count + 1}",
+            example: "[[count fruit]; [1 'apple']] | upsert count {|f| $f.count + 1}",
             result: Some(Value::List { vals: vec![Value::Record { cols: vec!["count".into(), "fruit".into()], vals: vec![Value::test_int(2), Value::test_string("apple")], span: Span::test_data()}], span: Span::test_data()}),
         }, Example {
             description: "Use in block form for more involved updating logic",
-            example: "echo [[project, authors]; ['nu', ['Andrés', 'JT', 'Yehuda']]] | upsert authors {|a| $a.authors | str join ','}",
+            example: "[[project, authors]; ['nu', ['Andrés', 'JT', 'Yehuda']]] | upsert authors {|a| $a.authors | str join ','}",
             result: Some(Value::List { vals: vec![Value::Record { cols: vec!["project".into(), "authors".into()], vals: vec![Value::test_string("nu"), Value::test_string("Andrés,JT,Yehuda")], span: Span::test_data()}], span: Span::test_data()}),
         },
         Example {
diff --git a/crates/nu-command/src/filters/where_.rs b/crates/nu-command/src/filters/where_.rs
index 3a29668c96..73f5114e5a 100644
--- a/crates/nu-command/src/filters/where_.rs
+++ b/crates/nu-command/src/filters/where_.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{CaptureBlock, Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, SyntaxShape, Value,
+    Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -21,6 +21,13 @@ impl Command for Where {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("where")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any)),
+                ),
+                (Type::Table(vec![]), Type::Table(vec![])),
+            ])
             .optional("cond", SyntaxShape::RowCondition, "condition")
             .named(
                 "block",
@@ -218,6 +225,26 @@ impl Command for Where {
 
     fn examples(&self) -> Vec<Example> {
         vec![
+            Example {
+                description: "Filter rows of a table according to a condition",
+                example: "[{a: 1} {a: 2}] | where a > 1",
+                result: Some(Value::List {
+                    vals: vec![Value::Record {
+                        cols: vec!["a".to_string()],
+                        vals: vec![Value::test_int(2)],
+                        span: Span::test_data(),
+                    }],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Filter items of a list according to a condition",
+                example: "[1 2] | where {|x| $x > 1}",
+                result: Some(Value::List {
+                    vals: vec![Value::test_int(2)],
+                    span: Span::test_data(),
+                }),
+            },
             Example {
                 description: "List all files in the current directory with sizes greater than 2kb",
                 example: "ls | where size > 2kb",
diff --git a/crates/nu-command/src/filters/window.rs b/crates/nu-command/src/filters/window.rs
index 9da690bd27..40c18f1a8c 100644
--- a/crates/nu-command/src/filters/window.rs
+++ b/crates/nu-command/src/filters/window.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,10 @@ impl Command for Window {
 
     fn signature(&self) -> Signature {
         Signature::build("window")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::List(Box::new(Type::Any)))),
+            )])
             .required("window_size", SyntaxShape::Int, "the size of each window")
             .named(
                 "stride",
@@ -155,7 +159,7 @@ impl Command for Window {
 
         vec![
             Example {
-                example: "echo [1 2 3 4] | window 2",
+                example: "[1 2 3 4] | window 2",
                 description: "A sliding window of two elements",
                 result: Some(Value::List {
                     vals: stream_test_1,
diff --git a/crates/nu-command/src/filters/wrap.rs b/crates/nu-command/src/filters/wrap.rs
index 2116dac56f..6778d8722d 100644
--- a/crates/nu-command/src/filters/wrap.rs
+++ b/crates/nu-command/src/filters/wrap.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, Signature,
-    Span, SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +20,7 @@ impl Command for Wrap {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("wrap")
+            .input_output_types(vec![(Type::List(Box::new(Type::Any)), Type::Table(vec![]))])
             .required("name", SyntaxShape::String, "the name of the column")
             .category(Category::Filters)
     }
@@ -68,7 +69,7 @@ impl Command for Wrap {
     fn examples(&self) -> Vec<Example> {
         vec![Example {
             description: "Wrap a list into a table with a given column name",
-            example: "echo [1 2 3] | wrap num",
+            example: "[1 2 3] | wrap num",
             result: Some(Value::List {
                 vals: vec![
                     Value::Record {
diff --git a/crates/nu-command/src/filters/zip.rs b/crates/nu-command/src/filters/zip.rs
index 95ad43f068..5415706c8d 100644
--- a/crates/nu-command/src/filters/zip.rs
+++ b/crates/nu-command/src/filters/zip.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, Signature,
-    Span, SyntaxShape, Value,
+    Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,6 +20,16 @@ impl Command for Zip {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("zip")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::List(Box::new(Type::Any)))),
+                ),
+                (
+                    Type::Range,
+                    Type::List(Box::new(Type::List(Box::new(Type::Any)))),
+                ),
+            ])
             .required("other", SyntaxShape::Any, "the other input")
             .category(Category::Filters)
     }
@@ -67,14 +77,33 @@ impl Command for Zip {
             span: Span::test_data(),
         };
 
-        vec![Example {
-            example: "1..3 | zip 4..6",
-            description: "Zip multiple streams and get one of the results",
-            result: Some(Value::List {
-                vals: vec![test_row_1, test_row_2, test_row_3],
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                example: "[1 2] | zip [3 4]",
+                description: "Zip two lists",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::List {
+                            vals: vec![Value::test_int(1), Value::test_int(3)],
+                            span: Span::test_data(),
+                        },
+                        Value::List {
+                            vals: vec![Value::test_int(2), Value::test_int(4)],
+                            span: Span::test_data(),
+                        },
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                example: "1..3 | zip 4..6",
+                description: "Zip two streams",
+                result: Some(Value::List {
+                    vals: vec![test_row_1, test_row_2, test_row_3],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 
     fn run(
diff --git a/crates/nu-command/src/formats/from/csv.rs b/crates/nu-command/src/formats/from/csv.rs
index 6da84f0bea..e71a07b6ba 100644
--- a/crates/nu-command/src/formats/from/csv.rs
+++ b/crates/nu-command/src/formats/from/csv.rs
@@ -3,7 +3,9 @@ use super::delimited::{from_delimited_data, trim_from_str};
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Value};
+use nu_protocol::{
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct FromCsv;
@@ -15,6 +17,7 @@ impl Command for FromCsv {
 
     fn signature(&self) -> Signature {
         Signature::build("from csv")
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
             .named(
                 "separator",
                 SyntaxShape::String,
@@ -54,8 +57,18 @@ impl Command for FromCsv {
         vec![
             Example {
                 description: "Convert comma-separated data to a table",
-                example: "open data.txt | from csv",
-                result: None,
+                example: "\"ColA,ColB\n1,2\" | from csv",
+                result: Some(Value::List {
+                    vals: vec![Value::Record {
+                        cols: vec!["ColA".to_string(), "ColB".to_string()],
+                        vals: vec![
+                            Value::test_int(1),
+                            Value::test_int(2),
+                        ],
+                        span: Span::test_data(),
+                    }],
+                    span: Span::test_data(),
+                })
             },
             Example {
                 description: "Convert comma-separated data to a table, ignoring headers",
diff --git a/crates/nu-command/src/formats/from/eml.rs b/crates/nu-command/src/formats/from/eml.rs
index 1880afc3b2..2da2079760 100644
--- a/crates/nu-command/src/formats/from/eml.rs
+++ b/crates/nu-command/src/formats/from/eml.rs
@@ -7,7 +7,7 @@ use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
 use nu_protocol::Config;
 use nu_protocol::{
-    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -22,6 +22,7 @@ impl Command for FromEml {
 
     fn signature(&self) -> Signature {
         Signature::build("from eml")
+            .input_output_types(vec![(Type::String, Type::Record(vec![]))])
             .named(
                 "preview-body",
                 SyntaxShape::Int,
@@ -32,7 +33,7 @@ impl Command for FromEml {
     }
 
     fn usage(&self) -> &str {
-        "Parse text as .eml and create table."
+        "Parse text as .eml and create record."
     }
 
     fn run(
@@ -52,7 +53,7 @@ impl Command for FromEml {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Convert eml structured data into table",
+                description: "Convert eml structured data into record",
                 example: "'From: test@email.com
 Subject: Welcome
 To: someone@somewhere.com
@@ -89,7 +90,7 @@ Test' | from eml",
                 }),
             },
             Example {
-                description: "Convert eml structured data into table",
+                description: "Convert eml structured data into record",
                 example: "'From: test@email.com
 Subject: Welcome
 To: someone@somewhere.com
diff --git a/crates/nu-command/src/formats/from/ics.rs b/crates/nu-command/src/formats/from/ics.rs
index 382d54935a..5a3990329a 100644
--- a/crates/nu-command/src/formats/from/ics.rs
+++ b/crates/nu-command/src/formats/from/ics.rs
@@ -6,7 +6,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, Value,
+    Spanned, Type, Value,
 };
 use std::io::BufReader;
 
@@ -19,7 +19,9 @@ impl Command for FromIcs {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("from ics").category(Category::Formats)
+        Signature::build("from ics")
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/formats/from/ini.rs b/crates/nu-command/src/formats/from/ini.rs
index 4a40e1c369..7c31d342f4 100644
--- a/crates/nu-command/src/formats/from/ini.rs
+++ b/crates/nu-command/src/formats/from/ini.rs
@@ -2,7 +2,8 @@ use indexmap::map::IndexMap;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -14,11 +15,13 @@ impl Command for FromIni {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("from ini").category(Category::Formats)
+        Signature::build("from ini")
+            .input_output_types(vec![(Type::String, Type::Record(vec![]))])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
-        "Parse text as .ini and create table"
+        "Parse text as .ini and create record"
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -26,7 +29,7 @@ impl Command for FromIni {
             example: "'[foo]
 a=1
 b=2' | from ini",
-            description: "Converts ini formatted string to table",
+            description: "Converts ini formatted string to record",
             result: Some(Value::Record {
                 cols: vec!["foo".to_string()],
                 vals: vec![Value::Record {
diff --git a/crates/nu-command/src/formats/from/json.rs b/crates/nu-command/src/formats/from/json.rs
index 8383923702..1ddaecb6e1 100644
--- a/crates/nu-command/src/formats/from/json.rs
+++ b/crates/nu-command/src/formats/from/json.rs
@@ -2,7 +2,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
-    Signature, Span, Value,
+    Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,7 @@ impl Command for FromJson {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("from json")
+            .input_output_types(vec![(Type::String, Type::Any)])
             .switch("objects", "treat each line as a separate value", Some('o'))
             .category(Category::Formats)
     }
diff --git a/crates/nu-command/src/formats/from/nuon.rs b/crates/nu-command/src/formats/from/nuon.rs
index 050c52be24..a11dfc0106 100644
--- a/crates/nu-command/src/formats/from/nuon.rs
+++ b/crates/nu-command/src/formats/from/nuon.rs
@@ -17,7 +17,9 @@ impl Command for FromNuon {
     }
 
     fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("from nuon").category(Category::Experimental)
+        Signature::build("from nuon")
+            .input_output_types(vec![(Type::String, Type::Any)])
+            .category(Category::Experimental)
     }
 
     fn examples(&self) -> Vec<Example> {
diff --git a/crates/nu-command/src/formats/from/ods.rs b/crates/nu-command/src/formats/from/ods.rs
index d309158e83..c2e5c710b7 100644
--- a/crates/nu-command/src/formats/from/ods.rs
+++ b/crates/nu-command/src/formats/from/ods.rs
@@ -4,7 +4,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 use std::io::Cursor;
 
@@ -18,6 +18,8 @@ impl Command for FromOds {
 
     fn signature(&self) -> Signature {
         Signature::build("from ods")
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
+            .allow_variants_without_examples(true)
             .named(
                 "sheets",
                 SyntaxShape::List(Box::new(SyntaxShape::String)),
diff --git a/crates/nu-command/src/formats/from/ssv.rs b/crates/nu-command/src/formats/from/ssv.rs
index 3efa0873f0..ff34b1fea2 100644
--- a/crates/nu-command/src/formats/from/ssv.rs
+++ b/crates/nu-command/src/formats/from/ssv.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,7 @@ impl Command for FromSsv {
 
     fn signature(&self) -> Signature {
         Signature::build("from ssv")
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
             .switch(
                 "noheaders",
                 "don't treat the first row as column names",
diff --git a/crates/nu-command/src/formats/from/toml.rs b/crates/nu-command/src/formats/from/toml.rs
index 6c3d5a6f93..2c52fa0d7c 100644
--- a/crates/nu-command/src/formats/from/toml.rs
+++ b/crates/nu-command/src/formats/from/toml.rs
@@ -1,7 +1,7 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -13,18 +13,20 @@ impl Command for FromToml {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("from toml").category(Category::Formats)
+        Signature::build("from toml")
+            .input_output_types(vec![(Type::String, Type::Record(vec![]))])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
-        "Parse text as .toml and create table."
+        "Parse text as .toml and create record."
     }
 
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
                 example: "'a = 1' | from toml",
-                description: "Converts toml formatted string to table",
+                description: "Converts toml formatted string to record",
                 result: Some(Value::Record {
                     cols: vec!["a".to_string()],
                     vals: vec![Value::Int {
@@ -37,7 +39,7 @@ impl Command for FromToml {
             Example {
                 example: "'a = 1
 b = [1, 2]' | from toml",
-                description: "Converts toml formatted string to table",
+                description: "Converts toml formatted string to record",
                 result: Some(Value::Record {
                     cols: vec!["a".to_string(), "b".to_string()],
                     vals: vec![
diff --git a/crates/nu-command/src/formats/from/tsv.rs b/crates/nu-command/src/formats/from/tsv.rs
index 270199052e..295daa35fa 100644
--- a/crates/nu-command/src/formats/from/tsv.rs
+++ b/crates/nu-command/src/formats/from/tsv.rs
@@ -3,7 +3,9 @@ use super::delimited::{from_delimited_data, trim_from_str};
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Value};
+use nu_protocol::{
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct FromTsv;
@@ -15,6 +17,7 @@ impl Command for FromTsv {
 
     fn signature(&self) -> Signature {
         Signature::build("from tsv")
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
             .switch(
                 "noheaders",
                 "don't treat the first row as column names",
@@ -46,6 +49,21 @@ impl Command for FromTsv {
 
     fn examples(&self) -> Vec<Example> {
         vec![
+            Example {
+                description: "Convert tab-separated data to a table",
+                example: "\"ColA\tColB\n1\t2\" | from tsv",
+                result: Some(Value::List {
+                    vals: vec![Value::Record {
+                        cols: vec!["ColA".to_string(), "ColB".to_string()],
+                        vals: vec![
+                            Value::test_int(1),
+                            Value::test_int(2),
+                        ],
+                        span: Span::test_data(),
+                    }],
+                    span: Span::test_data(),
+                })
+            },
             Example {
                 description: "Create a tsv file with header columns and open it",
                 example: r#"$'c1(char tab)c2(char tab)c3(char nl)1(char tab)2(char tab)3' | save tsv-data | open tsv-data | from tsv"#,
diff --git a/crates/nu-command/src/formats/from/url.rs b/crates/nu-command/src/formats/from/url.rs
index 630f57f226..2b89956d8b 100644
--- a/crates/nu-command/src/formats/from/url.rs
+++ b/crates/nu-command/src/formats/from/url.rs
@@ -1,6 +1,8 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Config, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{
+    Category, Config, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct FromUrl;
@@ -11,11 +13,13 @@ impl Command for FromUrl {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("from url").category(Category::Formats)
+        Signature::build("from url")
+            .input_output_types(vec![(Type::String, Type::Record(vec![]))])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
-        "Parse url-encoded string as a table."
+        "Parse url-encoded string as a record."
     }
 
     fn run(
@@ -33,7 +37,7 @@ impl Command for FromUrl {
     fn examples(&self) -> Vec<Example> {
         vec![Example {
             example: "'bread=baguette&cheese=comt%C3%A9&meat=ham&fat=butter' | from url",
-            description: "Convert url encoded string into a table",
+            description: "Convert url encoded string into a record",
             result: Some(Value::Record {
                 cols: vec![
                     "bread".to_string(),
diff --git a/crates/nu-command/src/formats/from/vcf.rs b/crates/nu-command/src/formats/from/vcf.rs
index d6fd84f191..cb42c6e42e 100644
--- a/crates/nu-command/src/formats/from/vcf.rs
+++ b/crates/nu-command/src/formats/from/vcf.rs
@@ -5,7 +5,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, Value,
+    Spanned, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,7 +17,9 @@ impl Command for FromVcf {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("from vcf").category(Category::Formats)
+        Signature::build("from vcf")
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/formats/from/xlsx.rs b/crates/nu-command/src/formats/from/xlsx.rs
index c2594f84c3..6e754c22aa 100644
--- a/crates/nu-command/src/formats/from/xlsx.rs
+++ b/crates/nu-command/src/formats/from/xlsx.rs
@@ -4,7 +4,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 use std::io::Cursor;
 
@@ -18,6 +18,8 @@ impl Command for FromXlsx {
 
     fn signature(&self) -> Signature {
         Signature::build("from xlsx")
+            .input_output_types(vec![(Type::Binary, Type::Table(vec![]))])
+            .allow_variants_without_examples(true)
             .named(
                 "sheets",
                 SyntaxShape::List(Box::new(SyntaxShape::String)),
diff --git a/crates/nu-command/src/formats/from/xml.rs b/crates/nu-command/src/formats/from/xml.rs
index 481f734b51..41fe153b1b 100644
--- a/crates/nu-command/src/formats/from/xml.rs
+++ b/crates/nu-command/src/formats/from/xml.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, Value,
+    Spanned, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,11 +15,13 @@ impl Command for FromXml {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("from xml").category(Category::Formats)
+        Signature::build("from xml")
+            .input_output_types(vec![(Type::String, Type::Record(vec![]))])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
-        "Parse text as .xml and create table."
+        "Parse text as .xml and create record."
     }
 
     fn run(
@@ -40,7 +42,7 @@ impl Command for FromXml {
 <note>
   <remember>Event</remember>
 </note>' | from xml"#,
-            description: "Converts xml formatted string to table",
+            description: "Converts xml formatted string to record",
             result: Some(Value::Record {
                 cols: vec!["note".to_string()],
                 vals: vec![Value::Record {
diff --git a/crates/nu-command/src/formats/from/yaml.rs b/crates/nu-command/src/formats/from/yaml.rs
index d7242f3ef8..3f07ae5efe 100644
--- a/crates/nu-command/src/formats/from/yaml.rs
+++ b/crates/nu-command/src/formats/from/yaml.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, Value,
+    Spanned, Type, Value,
 };
 use serde::de::Deserialize;
 use std::collections::HashMap;
@@ -17,7 +17,9 @@ impl Command for FromYaml {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("from yaml").category(Category::Formats)
+        Signature::build("from yaml")
+            .input_output_types(vec![(Type::String, Type::Any)])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/formats/to/csv.rs b/crates/nu-command/src/formats/to/csv.rs
index 2ad25294e1..97498420ab 100644
--- a/crates/nu-command/src/formats/to/csv.rs
+++ b/crates/nu-command/src/formats/to/csv.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Config, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,7 @@ impl Command for ToCsv {
 
     fn signature(&self) -> Signature {
         Signature::build("to csv")
+            .input_output_types(vec![(Type::Any, Type::String)])
             .named(
                 "separator",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/formats/to/html.rs b/crates/nu-command/src/formats/to/html.rs
index 5382558f91..ca689b7991 100644
--- a/crates/nu-command/src/formats/to/html.rs
+++ b/crates/nu-command/src/formats/to/html.rs
@@ -5,7 +5,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 use rust_embed::RustEmbed;
 use serde::{Deserialize, Serialize};
@@ -90,6 +90,7 @@ impl Command for ToHtml {
 
     fn signature(&self) -> Signature {
         Signature::build("to html")
+            .input_output_types(vec![(Type::Any, Type::String)])
             .switch("html-color", "change ansi colors to html colors", Some('c'))
             .switch("no-color", "remove all ansi colors in output", Some('n'))
             .switch(
diff --git a/crates/nu-command/src/formats/to/json.rs b/crates/nu-command/src/formats/to/json.rs
index d786db8483..0ab96681cd 100644
--- a/crates/nu-command/src/formats/to/json.rs
+++ b/crates/nu-command/src/formats/to/json.rs
@@ -2,7 +2,8 @@ use nu_engine::CallExt;
 use nu_protocol::ast::{Call, PathMember};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +16,7 @@ impl Command for ToJson {
 
     fn signature(&self) -> Signature {
         Signature::build("to json")
+            .input_output_types(vec![(Type::Any, Type::String)])
             .switch("raw", "remove all of the whitespace", Some('r'))
             .named(
                 "indent",
diff --git a/crates/nu-command/src/formats/to/md.rs b/crates/nu-command/src/formats/to/md.rs
index 44f5d155a4..3035f92288 100644
--- a/crates/nu-command/src/formats/to/md.rs
+++ b/crates/nu-command/src/formats/to/md.rs
@@ -3,7 +3,8 @@ use indexmap::map::IndexMap;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +17,7 @@ impl Command for ToMd {
 
     fn signature(&self) -> Signature {
         Signature::build("to md")
+            .input_output_types(vec![(Type::Any, Type::String)])
             .switch(
                 "pretty",
                 "Formats the Markdown table to vertically align items",
diff --git a/crates/nu-command/src/formats/to/nuon.rs b/crates/nu-command/src/formats/to/nuon.rs
index b57f2f8cd7..99bcd3b716 100644
--- a/crates/nu-command/src/formats/to/nuon.rs
+++ b/crates/nu-command/src/formats/to/nuon.rs
@@ -4,7 +4,7 @@ use nu_parser::escape_quote_string;
 use nu_protocol::ast::{Call, RangeInclusion};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,7 +16,9 @@ impl Command for ToNuon {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("to nuon").category(Category::Experimental)
+        Signature::build("to nuon")
+            .input_output_types(vec![(Type::Any, Type::String)])
+            .category(Category::Experimental)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/formats/to/text.rs b/crates/nu-command/src/formats/to/text.rs
index 9551ee156b..cb7da20cec 100644
--- a/crates/nu-command/src/formats/to/text.rs
+++ b/crates/nu-command/src/formats/to/text.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
     format_duration, format_filesize_from_conf, Category, Config, Example, IntoPipelineData,
-    PipelineData, ShellError, Signature, Value,
+    PipelineData, ShellError, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,7 +15,9 @@ impl Command for ToText {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("to text").category(Category::Formats)
+        Signature::build("to text")
+            .input_output_types(vec![(Type::Any, Type::String)])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/formats/to/toml.rs b/crates/nu-command/src/formats/to/toml.rs
index 4fd22d887f..1423d4817a 100644
--- a/crates/nu-command/src/formats/to/toml.rs
+++ b/crates/nu-command/src/formats/to/toml.rs
@@ -13,7 +13,9 @@ impl Command for ToToml {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("to toml").category(Category::Formats)
+        Signature::build("to toml")
+            .input_output_types(vec![(Type::Any, Type::String)])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/formats/to/tsv.rs b/crates/nu-command/src/formats/to/tsv.rs
index 8efca319e3..a4b3f59b6b 100644
--- a/crates/nu-command/src/formats/to/tsv.rs
+++ b/crates/nu-command/src/formats/to/tsv.rs
@@ -1,7 +1,9 @@
 use crate::formats::to::delimited::to_delimited_data;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Config, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{
+    Category, Config, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct ToTsv;
@@ -13,6 +15,7 @@ impl Command for ToTsv {
 
     fn signature(&self) -> Signature {
         Signature::build("to tsv")
+            .input_output_types(vec![(Type::Any, Type::String)])
             .switch(
                 "noheaders",
                 "do not output the column names as the first row",
diff --git a/crates/nu-command/src/formats/to/url.rs b/crates/nu-command/src/formats/to/url.rs
index 80aecfe8c9..046ec6ae41 100644
--- a/crates/nu-command/src/formats/to/url.rs
+++ b/crates/nu-command/src/formats/to/url.rs
@@ -1,7 +1,7 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -13,7 +13,9 @@ impl Command for ToUrl {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("to url").category(Category::Formats)
+        Signature::build("to url")
+            .input_output_types(vec![(Type::Table(vec![]), Type::String)])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/formats/to/xml.rs b/crates/nu-command/src/formats/to/xml.rs
index c6fb7f8eb0..13333e89dc 100644
--- a/crates/nu-command/src/formats/to/xml.rs
+++ b/crates/nu-command/src/formats/to/xml.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, SyntaxShape, Value,
+    Spanned, SyntaxShape, Type, Value,
 };
 use quick_xml::events::{BytesEnd, BytesStart, BytesText, Event};
 use std::collections::HashSet;
@@ -21,6 +21,7 @@ impl Command for ToXml {
 
     fn signature(&self) -> Signature {
         Signature::build("to xml")
+            .input_output_types(vec![(Type::Record(vec![]), Type::String)])
             .named(
                 "pretty",
                 SyntaxShape::Int,
diff --git a/crates/nu-command/src/formats/to/yaml.rs b/crates/nu-command/src/formats/to/yaml.rs
index b283805188..2009a14422 100644
--- a/crates/nu-command/src/formats/to/yaml.rs
+++ b/crates/nu-command/src/formats/to/yaml.rs
@@ -1,7 +1,7 @@
 use nu_protocol::ast::{Call, PathMember};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -13,7 +13,9 @@ impl Command for ToYaml {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("to yaml").category(Category::Formats)
+        Signature::build("to yaml")
+            .input_output_types(vec![(Type::Any, Type::String)])
+            .category(Category::Formats)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/generators/seq.rs b/crates/nu-command/src/generators/seq.rs
index 3ec9c15f57..e455ac7ae2 100644
--- a/crates/nu-command/src/generators/seq.rs
+++ b/crates/nu-command/src/generators/seq.rs
@@ -3,7 +3,7 @@ use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 use std::cmp;
 
@@ -17,6 +17,11 @@ impl Command for Seq {
 
     fn signature(&self) -> Signature {
         Signature::build("seq")
+            .input_output_types(vec![
+                (Type::Nothing, Type::List(Box::new(Type::Number))),
+                // -s flag
+                (Type::Nothing, Type::String),
+            ])
             .rest("rest", SyntaxShape::Number, "sequence values")
             .named(
                 "separator",
diff --git a/crates/nu-command/src/generators/seq_char.rs b/crates/nu-command/src/generators/seq_char.rs
index 15f11a75b2..528615603f 100644
--- a/crates/nu-command/src/generators/seq_char.rs
+++ b/crates/nu-command/src/generators/seq_char.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     ast::Call, Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, SyntaxShape, Value,
+    Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,10 @@ impl Command for SeqChar {
 
     fn signature(&self) -> Signature {
         Signature::build("seq char")
+            .input_output_types(vec![
+                (Type::Nothing, Type::List(Box::new(Type::Any))),
+                (Type::Nothing, Type::String),
+            ])
             .rest("rest", SyntaxShape::String, "sequence chars")
             .named(
                 "separator",
diff --git a/crates/nu-command/src/generators/seq_date.rs b/crates/nu-command/src/generators/seq_date.rs
index c3ed00bb21..e9bbb97395 100644
--- a/crates/nu-command/src/generators/seq_date.rs
+++ b/crates/nu-command/src/generators/seq_date.rs
@@ -5,7 +5,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -22,6 +22,7 @@ impl Command for SeqDate {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("seq date")
+            .input_output_types(vec![(Type::Nothing, Type::List(Box::new(Type::String)))])
             .named(
                 "separator",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/hash/generic_digest.rs b/crates/nu-command/src/hash/generic_digest.rs
index 6fada940ad..212ee33fac 100644
--- a/crates/nu-command/src/hash/generic_digest.rs
+++ b/crates/nu-command/src/hash/generic_digest.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::{Call, CellPath};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Span;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value};
 use std::marker::PhantomData;
 
 pub trait HashDigest: digest::Digest + Clone {
@@ -50,6 +50,10 @@ where
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![
+                (Type::String, Type::String),
+                (Type::String, Type::Binary),
+            ])
             .switch(
                 "binary",
                 "Output binary instead of hexadecimal representation",
diff --git a/crates/nu-command/src/hash/md5.rs b/crates/nu-command/src/hash/md5.rs
index a27083596e..f5bd62915a 100644
--- a/crates/nu-command/src/hash/md5.rs
+++ b/crates/nu-command/src/hash/md5.rs
@@ -12,7 +12,7 @@ impl HashDigest for Md5 {
     fn examples() -> Vec<Example> {
         vec![
             Example {
-                description: "get a hexadecimaly encoded string of the md5 digest of a string",
+                description: "Return the md5 hash of a string, hex-encoded",
                 example: "echo 'abcdefghijklmnopqrstuvwxyz' | hash md5",
                 result: Some(Value::String {
                     val: "c3fcd3d76192e4007dfb496cca67e13b".to_owned(),
@@ -20,7 +20,7 @@ impl HashDigest for Md5 {
                 }),
             },
             Example {
-                description: "get the md5 digest of a string in binary",
+                description: "Return the md5 hash of a string, as binary",
                 example: "echo 'abcdefghijklmnopqrstuvwxyz' | hash md5 --binary",
                 result: Some(Value::Binary {
                     val: vec![
@@ -31,7 +31,7 @@ impl HashDigest for Md5 {
                 }),
             },
             Example {
-                description: "md5 encode a file",
+                description: "Return the md5 hash of a file's contents",
                 example: "open ./nu_0_24_1_windows.zip | hash md5",
                 result: None,
             },
diff --git a/crates/nu-command/src/hash/sha256.rs b/crates/nu-command/src/hash/sha256.rs
index 2852ef6014..d70ab96381 100644
--- a/crates/nu-command/src/hash/sha256.rs
+++ b/crates/nu-command/src/hash/sha256.rs
@@ -12,7 +12,7 @@ impl HashDigest for Sha256 {
     fn examples() -> Vec<Example> {
         vec![
             Example {
-                description: "get a hexadecimaly encoded string of the sha256 digest of a string",
+                description: "Return the sha256 hash of a string, hex-encoded",
                 example: "echo 'abcdefghijklmnopqrstuvwxyz' | hash sha256",
                 result: Some(Value::String {
                     val: "71c480df93d6ae2f1efad1447c66c9525e316218cf51fc8d9ed832f2daf18b73"
@@ -21,7 +21,7 @@ impl HashDigest for Sha256 {
                 }),
             },
             Example {
-                description: "get the sha256 digest of a string in binary",
+                description: "Return the sha256 hash of a string, as binary",
                 example: "echo 'abcdefghijklmnopqrstuvwxyz' | hash sha256 --binary",
                 result: Some(Value::Binary {
                     val: vec![
@@ -33,7 +33,7 @@ impl HashDigest for Sha256 {
                 }),
             },
             Example {
-                description: "sha256 encode a file",
+                description: "Return the sha256 hash of a file's contents",
                 example: "open ./nu_0_24_1_windows.zip | hash sha256",
                 result: None,
             },
diff --git a/crates/nu-command/src/math/abs.rs b/crates/nu-command/src/math/abs.rs
index 9cf131ce46..c3deb8b0fc 100644
--- a/crates/nu-command/src/math/abs.rs
+++ b/crates/nu-command/src/math/abs.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -11,11 +11,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math abs").category(Category::Math)
+        Signature::build("math abs")
+            .input_output_types(vec![(Type::Number, Type::Number)])
+            .vectorizes_over_list(true)
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Returns absolute values of a list of numbers"
+        "Returns the absolute value of a number"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -38,7 +41,7 @@ impl Command for SubCommand {
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Get absolute of each value in a list of numbers",
+            description: "Compute absolute value of each number in a list of numbers",
             example: "[-50 -100.0 25] | math abs",
             result: Some(Value::List {
                 vals: vec![
diff --git a/crates/nu-command/src/math/avg.rs b/crates/nu-command/src/math/avg.rs
index dac06913e4..555f44eb09 100644
--- a/crates/nu-command/src/math/avg.rs
+++ b/crates/nu-command/src/math/avg.rs
@@ -2,7 +2,7 @@ use crate::math::reducers::{reducer_for, Reduce};
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,11 +13,13 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math avg").category(Category::Math)
+        Signature::build("math avg")
+            .input_output_types(vec![(Type::List(Box::new(Type::Number)), Type::Number)])
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Finds the average of a list of numbers or tables"
+        "Returns the average of a list of numbers"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -36,7 +38,7 @@ impl Command for SubCommand {
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Get the average of a list of numbers",
+            description: "Compute the average of a list of numbers",
             example: "[-50 100.0 25] | math avg",
             result: Some(Value::Float {
                 val: 25.0,
diff --git a/crates/nu-command/src/math/ceil.rs b/crates/nu-command/src/math/ceil.rs
index 3aa6697e02..df13901ff0 100644
--- a/crates/nu-command/src/math/ceil.rs
+++ b/crates/nu-command/src/math/ceil.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -11,11 +11,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math ceil").category(Category::Math)
+        Signature::build("math ceil")
+            .input_output_types(vec![(Type::Number, Type::Int)])
+            .vectorizes_over_list(true)
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Applies the ceil function to a list of numbers"
+        "Returns the ceil of a number (smallest integer greater than or equal to that number)"
     }
 
     fn search_terms(&self) -> Vec<&str> {
diff --git a/crates/nu-command/src/math/eval.rs b/crates/nu-command/src/math/eval.rs
index 28bc02b56a..38cec52fca 100644
--- a/crates/nu-command/src/math/eval.rs
+++ b/crates/nu-command/src/math/eval.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -23,6 +23,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("math eval")
+            .input_output_types(vec![(Type::String, Type::Number)])
             .optional(
                 "math expression",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/math/floor.rs b/crates/nu-command/src/math/floor.rs
index cc7a4ad48b..c718bb482f 100644
--- a/crates/nu-command/src/math/floor.rs
+++ b/crates/nu-command/src/math/floor.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -11,11 +11,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math floor").category(Category::Math)
+        Signature::build("math floor")
+            .input_output_types(vec![(Type::Number, Type::Int)])
+            .vectorizes_over_list(true)
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Applies the floor function to a list of numbers"
+        "Returns the floor of a number (largest integer less than or equal to that number)"
     }
 
     fn search_terms(&self) -> Vec<&str> {
diff --git a/crates/nu-command/src/math/max.rs b/crates/nu-command/src/math/max.rs
index afccd71f71..be71eb6de3 100644
--- a/crates/nu-command/src/math/max.rs
+++ b/crates/nu-command/src/math/max.rs
@@ -2,7 +2,7 @@ use crate::math::reducers::{reducer_for, Reduce};
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,11 +13,16 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math max").category(Category::Math)
+        Signature::build("math max")
+            .input_output_types(vec![
+                (Type::List(Box::new(Type::Number)), Type::Number),
+                (Type::Table(vec![]), Type::Record(vec![])),
+            ])
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Finds the maximum within a list of numbers or tables"
+        "Returns the maximum of a list of numbers, or of columns in a table"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -35,11 +40,22 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Find the maximum of list of numbers",
-            example: "[-50 100 25] | math max",
-            result: Some(Value::test_int(100)),
-        }]
+        vec![
+            Example {
+                description: "Find the maximum of list of numbers",
+                example: "[-50 100 25] | math max",
+                result: Some(Value::test_int(100)),
+            },
+            Example {
+                description: "Find the maxima of the columns of a table",
+                example: "[{a: 1 b: 3} {a: 2 b: -1}] | math max",
+                result: Some(Value::Record {
+                    cols: vec!["a".to_string(), "b".to_string()],
+                    vals: vec![Value::test_int(2), Value::test_int(3)],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 }
 
diff --git a/crates/nu-command/src/math/median.rs b/crates/nu-command/src/math/median.rs
index a9dfebe4ab..ade21335c3 100644
--- a/crates/nu-command/src/math/median.rs
+++ b/crates/nu-command/src/math/median.rs
@@ -4,7 +4,7 @@ use crate::math::avg::average;
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -15,11 +15,16 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math median").category(Category::Math)
+        Signature::build("math median")
+            .input_output_types(vec![
+                (Type::List(Box::new(Type::Number)), Type::Number),
+                (Type::Table(vec![]), Type::Record(vec![])),
+            ])
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Gets the median of a list of numbers"
+        "Computes the median of a list of numbers"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -37,14 +42,25 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Get the median of a list of numbers",
-            example: "[3 8 9 12 12 15] | math median",
-            result: Some(Value::Float {
-                val: 10.5,
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                description: "Compute the median of a list of numbers",
+                example: "[3 8 9 12 12 15] | math median",
+                result: Some(Value::Float {
+                    val: 10.5,
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Compute the medians of the columns of a table",
+                example: "[{a: 1 b: 3} {a: 2 b: -1} {a: -3 b: 5}] | math median",
+                result: Some(Value::Record {
+                    cols: vec!["a".to_string(), "b".to_string()],
+                    vals: vec![Value::test_int(1), Value::test_int(3)],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 }
 
diff --git a/crates/nu-command/src/math/min.rs b/crates/nu-command/src/math/min.rs
index 1b637d86d4..d2f62a42e3 100644
--- a/crates/nu-command/src/math/min.rs
+++ b/crates/nu-command/src/math/min.rs
@@ -2,7 +2,7 @@ use crate::math::reducers::{reducer_for, Reduce};
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,7 +13,12 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math min").category(Category::Math)
+        Signature::build("math min")
+            .input_output_types(vec![
+                (Type::List(Box::new(Type::Number)), Type::Number),
+                (Type::Table(vec![]), Type::Record(vec![])),
+            ])
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
@@ -35,11 +40,22 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Get the minimum of a list of numbers",
-            example: "[-50 100 25] | math min",
-            result: Some(Value::test_int(-50)),
-        }]
+        vec![
+            Example {
+                description: "Compute the minimum of a list of numbers",
+                example: "[-50 100 25] | math min",
+                result: Some(Value::test_int(-50)),
+            },
+            Example {
+                description: "Compute the minima of the columns of a table",
+                example: "[{a: 1 b: 3} {a: 2 b: -1}] | math min",
+                result: Some(Value::Record {
+                    cols: vec!["a".to_string(), "b".to_string()],
+                    vals: vec![Value::test_int(1), Value::test_int(-1)],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 }
 
diff --git a/crates/nu-command/src/math/mode.rs b/crates/nu-command/src/math/mode.rs
index 2a57059c9c..cf34c69784 100644
--- a/crates/nu-command/src/math/mode.rs
+++ b/crates/nu-command/src/math/mode.rs
@@ -1,7 +1,7 @@
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 use std::cmp::Ordering;
 
 #[derive(Clone)]
@@ -36,11 +36,19 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math mode").category(Category::Math)
+        Signature::build("math mode")
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Number)),
+                    Type::List(Box::new(Type::Number)),
+                ),
+                (Type::Table(vec![]), Type::Record(vec![])),
+            ])
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Gets the most frequent element(s) from a list of numbers or tables"
+        "Returns the most frequent element(s) from a list of numbers or tables"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -58,14 +66,34 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Get the mode(s) of a list of numbers",
-            example: "[3 3 9 12 12 15] | math mode",
-            result: Some(Value::List {
-                vals: vec![Value::test_int(3), Value::test_int(12)],
-                span: Span::test_data(),
-            }),
-        }]
+        vec![
+            Example {
+                description: "Compute the mode(s) of a list of numbers",
+                example: "[3 3 9 12 12 15] | math mode",
+                result: Some(Value::List {
+                    vals: vec![Value::test_int(3), Value::test_int(12)],
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Compute the mode(s) of the columns of a table",
+                example: "[{a: 1 b: 3} {a: 2 b: -1} {a: 1 b: 5}] | math mode",
+                result: Some(Value::Record {
+                    cols: vec!["a".to_string(), "b".to_string()],
+                    vals: vec![
+                        Value::List {
+                            vals: vec![Value::test_int(1)],
+                            span: Span::test_data(),
+                        },
+                        Value::List {
+                            vals: vec![Value::test_int(-1), Value::test_int(3), Value::test_int(5)],
+                            span: Span::test_data(),
+                        },
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
+        ]
     }
 }
 
diff --git a/crates/nu-command/src/math/product.rs b/crates/nu-command/src/math/product.rs
index 1fcfd197b2..17071c2c1f 100644
--- a/crates/nu-command/src/math/product.rs
+++ b/crates/nu-command/src/math/product.rs
@@ -2,7 +2,7 @@ use crate::math::reducers::{reducer_for, Reduce};
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,11 +13,13 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math product").category(Category::Math)
+        Signature::build("math product")
+            .input_output_types(vec![(Type::List(Box::new(Type::Number)), Type::Number)])
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Finds the product of a list of numbers or tables"
+        "Returns the product of a list of numbers or the products of each column of a table"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -36,7 +38,7 @@ impl Command for SubCommand {
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Get the product of a list of numbers",
+            description: "Compute the product of a list of numbers",
             example: "[2 3 3 4] | math product",
             result: Some(Value::test_int(72)),
         }]
diff --git a/crates/nu-command/src/math/round.rs b/crates/nu-command/src/math/round.rs
index 8f47e24253..739313bb41 100644
--- a/crates/nu-command/src/math/round.rs
+++ b/crates/nu-command/src/math/round.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("math round")
+            .input_output_types(vec![(Type::Number, Type::Number)])
+            .vectorizes_over_list(true)
             .named(
                 "precision",
                 SyntaxShape::Number,
@@ -25,11 +27,11 @@ impl Command for SubCommand {
     }
 
     fn usage(&self) -> &str {
-        "Applies the round function to a list of numbers"
+        "Returns the input number rounded to the specified precision"
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["approx", "rough"]
+        vec!["approx", "closest", "nearest"]
     }
 
     fn run(
diff --git a/crates/nu-command/src/math/sqrt.rs b/crates/nu-command/src/math/sqrt.rs
index 2a38a76dc1..d04754fc16 100644
--- a/crates/nu-command/src/math/sqrt.rs
+++ b/crates/nu-command/src/math/sqrt.rs
@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -11,11 +11,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math sqrt").category(Category::Math)
+        Signature::build("math sqrt")
+            .input_output_types(vec![(Type::Number, Type::Number)])
+            .vectorizes_over_list(true)
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Applies the square root function to a list of numbers"
+        "Returns the square root of the input number"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -38,7 +41,7 @@ impl Command for SubCommand {
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Apply the square root function to a list of numbers",
+            description: "Compute the square root of each number in a list",
             example: "[9 16] | math sqrt",
             result: Some(Value::List {
                 vals: vec![Value::test_int(3), Value::test_int(4)],
diff --git a/crates/nu-command/src/math/stddev.rs b/crates/nu-command/src/math/stddev.rs
index cb76fd40c5..544ffe64fe 100644
--- a/crates/nu-command/src/math/stddev.rs
+++ b/crates/nu-command/src/math/stddev.rs
@@ -2,7 +2,7 @@ use super::variance::compute_variance as variance;
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -14,12 +14,17 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("math stddev")
-            .switch("sample", "calculate sample standard deviation", Some('s'))
+            .input_output_types(vec![(Type::List(Box::new(Type::Number)), Type::Number)])
+            .switch(
+                "sample",
+                "calculate sample standard deviation (i.e. using N-1 as the denominator)",
+                Some('s'),
+            )
             .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Finds the stddev of a list of numbers or tables"
+        "Returns the standard deviation of a list of numbers, or of each column in a table"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -47,7 +52,7 @@ impl Command for SubCommand {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Get the stddev of a list of numbers",
+                description: "Compute the standard deviation of a list of numbers",
                 example: "[1 2 3 4 5] | math stddev",
                 result: Some(Value::Float {
                     val: std::f64::consts::SQRT_2,
@@ -55,7 +60,7 @@ impl Command for SubCommand {
                 }),
             },
             Example {
-                description: "Get the sample stddev of a list of numbers",
+                description: "Compute the sample standard deviation of a list of numbers",
                 example: "[1 2 3 4 5] | math stddev -s",
                 result: Some(Value::Float {
                     val: 1.5811388300841898,
diff --git a/crates/nu-command/src/math/sum.rs b/crates/nu-command/src/math/sum.rs
index e341b099ec..44138ab3ac 100644
--- a/crates/nu-command/src/math/sum.rs
+++ b/crates/nu-command/src/math/sum.rs
@@ -2,7 +2,7 @@ use crate::math::reducers::{reducer_for, Reduce};
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,15 +13,17 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("math sum").category(Category::Math)
+        Signature::build("math sum")
+            .input_output_types(vec![(Type::List(Box::new(Type::Number)), Type::Number)])
+            .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Finds the sum of a list of numbers or tables"
+        "Returns the sum of a list of numbers or of each column in a table"
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["plus", "add", "+"]
+        vec!["plus", "add", "total", "+"]
     }
 
     fn run(
diff --git a/crates/nu-command/src/math/variance.rs b/crates/nu-command/src/math/variance.rs
index d70eba7634..3a3a2859aa 100644
--- a/crates/nu-command/src/math/variance.rs
+++ b/crates/nu-command/src/math/variance.rs
@@ -1,7 +1,7 @@
 use crate::math::utils::run_with_function;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,12 +13,17 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("math variance")
-            .switch("sample", "calculate sample variance", Some('s'))
+            .input_output_types(vec![(Type::List(Box::new(Type::Number)), Type::Number)])
+            .switch(
+                "sample",
+                "calculate sample variance (i.e. using N-1 as the denominator)",
+                Some('s'),
+            )
             .category(Category::Math)
     }
 
     fn usage(&self) -> &str {
-        "Finds the variance of a list of numbers or tables"
+        "Returns the variance of a list of numbers or of each column in a table"
     }
 
     fn search_terms(&self) -> Vec<&str> {
diff --git a/crates/nu-command/src/network/fetch.rs b/crates/nu-command/src/network/fetch.rs
index 994f094ab4..9452473510 100644
--- a/crates/nu-command/src/network/fetch.rs
+++ b/crates/nu-command/src/network/fetch.rs
@@ -297,18 +297,18 @@ impl Command for SubCommand {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Fetch content from url.com",
-                example: "fetch url.com",
+                description: "Fetch content from example.com",
+                example: "fetch https://www.example.com",
                 result: None,
             },
             Example {
-                description: "Fetch content from url.com, with username and password",
-                example: "fetch -u myuser -p mypass url.com",
+                description: "Fetch content from example.com, with username and password",
+                example: "fetch -u myuser -p mypass https://www.example.com",
                 result: None,
             },
             Example {
-                description: "Fetch content from url.com, with custom header",
-                example: "fetch -H [my-header-key my-header-value] url.com",
+                description: "Fetch content from example.com, with custom header",
+                example: "fetch -H [my-header-key my-header-value] https://www.example.com",
                 result: None,
             },
         ]
diff --git a/crates/nu-command/src/network/url/host.rs b/crates/nu-command/src/network/url/host.rs
index 9072bdf321..cff0fc471b 100644
--- a/crates/nu-command/src/network/url/host.rs
+++ b/crates/nu-command/src/network/url/host.rs
@@ -1,7 +1,7 @@
 use super::{operator, url};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,6 +13,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("url host")
+            .input_output_types(vec![(Type::String, Type::String)])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/network/url/path.rs b/crates/nu-command/src/network/url/path.rs
index a6bf7a000d..0bdcfd0b97 100644
--- a/crates/nu-command/src/network/url/path.rs
+++ b/crates/nu-command/src/network/url/path.rs
@@ -1,7 +1,7 @@
 use super::{operator, url};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,6 +13,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("url path")
+            .input_output_types(vec![(Type::String, Type::String)])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/network/url/query.rs b/crates/nu-command/src/network/url/query.rs
index 195c1fafd5..729c495032 100644
--- a/crates/nu-command/src/network/url/query.rs
+++ b/crates/nu-command/src/network/url/query.rs
@@ -1,7 +1,7 @@
 use super::{operator, url};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,6 +13,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("url query")
+            .input_output_types(vec![(Type::String, Type::String)])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/network/url/scheme.rs b/crates/nu-command/src/network/url/scheme.rs
index 23b4f42cf3..9ecc9af710 100644
--- a/crates/nu-command/src/network/url/scheme.rs
+++ b/crates/nu-command/src/network/url/scheme.rs
@@ -1,7 +1,7 @@
 use super::{operator, url};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,6 +13,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("url scheme")
+            .input_output_types(vec![(Type::String, Type::String)])
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/network/url/url_.rs b/crates/nu-command/src/network/url/url_.rs
index 52c4818823..53dc127086 100644
--- a/crates/nu-command/src/network/url/url_.rs
+++ b/crates/nu-command/src/network/url/url_.rs
@@ -2,7 +2,7 @@ use nu_engine::get_full_help;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, IntoPipelineData, PipelineData, Signature, Value,
+    Category, IntoPipelineData, PipelineData, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,7 +14,9 @@ impl Command for Url {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("url").category(Category::Network)
+        Signature::build("url")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .category(Category::Network)
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/path/basename.rs b/crates/nu-command/src/path/basename.rs
index 223a86d5c1..bab776af60 100644
--- a/crates/nu-command/src/path/basename.rs
+++ b/crates/nu-command/src/path/basename.rs
@@ -1,7 +1,7 @@
 use std::path::Path;
 
 use nu_engine::CallExt;
-use nu_protocol::{engine::Command, Example, Signature, Span, Spanned, SyntaxShape, Value};
+use nu_protocol::{engine::Command, Example, Signature, Span, Spanned, SyntaxShape, Type, Value};
 
 use super::PathSubcommandArguments;
 
@@ -26,6 +26,11 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("path basename")
+            .input_output_types(vec![
+                (Type::String, Type::String),
+                // TODO: Why do these commands not use CellPaths in a standard way?
+                (Type::Table(vec![]), Type::Table(vec![])),
+            ])
             .named(
                 "columns",
                 SyntaxShape::Table,
diff --git a/crates/nu-command/src/path/dirname.rs b/crates/nu-command/src/path/dirname.rs
index 061fa0eb06..6fbd170e60 100644
--- a/crates/nu-command/src/path/dirname.rs
+++ b/crates/nu-command/src/path/dirname.rs
@@ -1,7 +1,7 @@
 use std::path::Path;
 
 use nu_engine::CallExt;
-use nu_protocol::{engine::Command, Example, Signature, Span, Spanned, SyntaxShape, Value};
+use nu_protocol::{engine::Command, Example, Signature, Span, Spanned, SyntaxShape, Type, Value};
 
 use super::PathSubcommandArguments;
 
@@ -27,6 +27,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("path dirname")
+            .input_output_types(vec![(Type::String, Type::String)])
             .named(
                 "columns",
                 SyntaxShape::Table,
diff --git a/crates/nu-command/src/path/exists.rs b/crates/nu-command/src/path/exists.rs
index e5dab5ef65..e00a6c2f39 100644
--- a/crates/nu-command/src/path/exists.rs
+++ b/crates/nu-command/src/path/exists.rs
@@ -2,7 +2,7 @@ use std::path::{Path, PathBuf};
 
 use nu_engine::{current_dir, CallExt};
 use nu_path::expand_path_with;
-use nu_protocol::{engine::Command, Example, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{engine::Command, Example, Signature, Span, SyntaxShape, Type, Value};
 
 use super::PathSubcommandArguments;
 
@@ -26,12 +26,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("path exists").named(
-            "columns",
-            SyntaxShape::Table,
-            "Optionally operate by column path",
-            Some('c'),
-        )
+        Signature::build("path exists")
+            .input_output_types(vec![(Type::String, Type::Bool)])
+            .named(
+                "columns",
+                SyntaxShape::Table,
+                "Optionally operate by column path",
+                Some('c'),
+            )
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/path/expand.rs b/crates/nu-command/src/path/expand.rs
index 0f11d04771..cece7a4d32 100644
--- a/crates/nu-command/src/path/expand.rs
+++ b/crates/nu-command/src/path/expand.rs
@@ -3,7 +3,9 @@ use std::path::Path;
 use nu_engine::env::current_dir_str;
 use nu_engine::CallExt;
 use nu_path::{canonicalize_with, expand_path_with};
-use nu_protocol::{engine::Command, Example, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{
+    engine::Command, Example, ShellError, Signature, Span, SyntaxShape, Type, Value,
+};
 
 use super::PathSubcommandArguments;
 
@@ -30,6 +32,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("path expand")
+            .input_output_types(vec![(Type::String, Type::String)])
             .switch(
                 "strict",
                 "Throw an error if the path could not be expanded",
diff --git a/crates/nu-command/src/path/join.rs b/crates/nu-command/src/path/join.rs
index 32e88e084a..2625f4a273 100644
--- a/crates/nu-command/src/path/join.rs
+++ b/crates/nu-command/src/path/join.rs
@@ -6,7 +6,7 @@ use std::{
 use nu_engine::CallExt;
 use nu_protocol::{
     engine::Command, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 use super::PathSubcommandArguments;
@@ -32,6 +32,11 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("path join")
+            .input_output_types(vec![
+                (Type::String, Type::String),
+                (Type::List(Box::new(Type::String)), Type::String),
+                (Type::Table(vec![]), Type::List(Box::new(Type::String))),
+            ])
             .named(
                 "columns",
                 SyntaxShape::Table,
diff --git a/crates/nu-command/src/path/parse.rs b/crates/nu-command/src/path/parse.rs
index 14b9b64db4..97aa6af5d5 100644
--- a/crates/nu-command/src/path/parse.rs
+++ b/crates/nu-command/src/path/parse.rs
@@ -3,7 +3,7 @@ use std::path::Path;
 use indexmap::IndexMap;
 use nu_engine::CallExt;
 use nu_protocol::{
-    engine::Command, Example, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    engine::Command, Example, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 use super::PathSubcommandArguments;
@@ -29,6 +29,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("path parse")
+            .input_output_types(vec![(Type::String, Type::Record(vec![]))])
             .named(
                 "columns",
                 SyntaxShape::Table,
diff --git a/crates/nu-command/src/path/relative_to.rs b/crates/nu-command/src/path/relative_to.rs
index 670d3ea7c9..b40b61f2e4 100644
--- a/crates/nu-command/src/path/relative_to.rs
+++ b/crates/nu-command/src/path/relative_to.rs
@@ -3,7 +3,7 @@ use std::path::Path;
 use nu_engine::CallExt;
 use nu_path::expand_to_real_path;
 use nu_protocol::{
-    engine::Command, Example, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    engine::Command, Example, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 use super::PathSubcommandArguments;
@@ -29,6 +29,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("path relative-to")
+            .input_output_types(vec![(Type::String, Type::String)])
             .required(
                 "path",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/path/split.rs b/crates/nu-command/src/path/split.rs
index 173c3bc853..cefb0f4d79 100644
--- a/crates/nu-command/src/path/split.rs
+++ b/crates/nu-command/src/path/split.rs
@@ -1,7 +1,9 @@
 use std::path::{Component, Path};
 
 use nu_engine::CallExt;
-use nu_protocol::{engine::Command, Example, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{
+    engine::Command, Example, ShellError, Signature, Span, SyntaxShape, Type, Value,
+};
 
 use super::PathSubcommandArguments;
 
@@ -24,12 +26,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("path split").named(
-            "columns",
-            SyntaxShape::Table,
-            "Optionally operate by column path",
-            Some('c'),
-        )
+        Signature::build("path split")
+            .input_output_types(vec![(Type::String, Type::List(Box::new(Type::String)))])
+            .named(
+                "columns",
+                SyntaxShape::Table,
+                "Optionally operate by column path",
+                Some('c'),
+            )
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/path/type.rs b/crates/nu-command/src/path/type.rs
index 2a5689a1ba..d142525675 100644
--- a/crates/nu-command/src/path/type.rs
+++ b/crates/nu-command/src/path/type.rs
@@ -1,7 +1,9 @@
 use std::path::Path;
 
 use nu_engine::CallExt;
-use nu_protocol::{engine::Command, Example, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{
+    engine::Command, Example, ShellError, Signature, Span, SyntaxShape, Type, Value,
+};
 
 use super::PathSubcommandArguments;
 
@@ -24,12 +26,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("path type").named(
-            "columns",
-            SyntaxShape::Table,
-            "Optionally operate by column path",
-            Some('c'),
-        )
+        Signature::build("path type")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .named(
+                "columns",
+                SyntaxShape::Table,
+                "Optionally operate by column path",
+                Some('c'),
+            )
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/platform/ansi/ansi_.rs b/crates/nu-command/src/platform/ansi/ansi_.rs
index 6750c289ab..f20e62027e 100644
--- a/crates/nu-command/src/platform/ansi/ansi_.rs
+++ b/crates/nu-command/src/platform/ansi/ansi_.rs
@@ -3,7 +3,7 @@ use nu_ansi_term::*;
 use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call, engine::Command, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData,
-    PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 use std::collections::HashMap;
 
@@ -202,6 +202,7 @@ impl Command for AnsiCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("ansi")
+            .input_output_types(vec![(Type::Nothing, Type::String)])
             .optional(
                 "code",
                 SyntaxShape::Any,
@@ -293,9 +294,13 @@ Format: #
             Example {
                 description: "Use ansi to color text (italic bright yellow on red 'Hello' with green bold 'Nu' and purple bold 'World')",
                 example: r#"[(ansi -e '3;93;41m') Hello (ansi reset) " " (ansi gb) Nu " " (ansi pb) World (ansi reset)] | str join"#,
-                result: Some(Value::test_string(
-                    "\u{1b}[3;93;41mHello\u{1b}[0m \u{1b}[1;32mNu \u{1b}[1;35mWorld\u{1b}[0m",
-                )),
+                result: None,
+                // Test disabled because the final expression in the pipeline is
+                // not the command being tested, and this violated assumptions
+                // made by the run-time input/output type-checking tests.
+                // result: Some(Value::test_string(
+                //     "\u{1b}[3;93;41mHello\u{1b}[0m \u{1b}[1;32mNu \u{1b}[1;35mWorld\u{1b}[0m",
+                // )),
             },
             Example {
                 description: "Use ansi to color text with a style (blue on red in bold)",
diff --git a/crates/nu-command/src/platform/ansi/strip.rs b/crates/nu-command/src/platform/ansi/strip.rs
index 8aa11d2d11..e18f4fe838 100644
--- a/crates/nu-command/src/platform/ansi/strip.rs
+++ b/crates/nu-command/src/platform/ansi/strip.rs
@@ -1,7 +1,7 @@
 use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call, ast::CellPath, engine::Command, engine::EngineState, engine::Stack, Category,
-    Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,6 +14,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("ansi strip")
+            .input_output_types(vec![(Type::String, Type::String)])
             .rest(
                 "column path",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/platform/sleep.rs b/crates/nu-command/src/platform/sleep.rs
index 4d883ab76c..da24a67ae4 100644
--- a/crates/nu-command/src/platform/sleep.rs
+++ b/crates/nu-command/src/platform/sleep.rs
@@ -2,7 +2,8 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
+    Type, Value,
 };
 use std::{
     sync::atomic::Ordering,
@@ -26,6 +27,7 @@ impl Command for Sleep {
 
     fn signature(&self) -> Signature {
         Signature::build("sleep")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .required("duration", SyntaxShape::Duration, "time to sleep")
             .rest("rest", SyntaxShape::Duration, "additional time")
             .category(Category::Platform)
@@ -75,18 +77,20 @@ impl Command for Sleep {
             Example {
                 description: "Sleep for 1sec",
                 example: "sleep 1sec",
-                result: None,
-            },
-            Example {
-                description: "Sleep for 3sec",
-                example: "sleep 1sec 1sec 1sec",
-                result: None,
-            },
-            Example {
-                description: "Send output after 1sec",
-                example: "sleep 1sec; echo done",
-                result: Some(Value::test_string("done")),
+                result: Some(Value::Nothing {
+                    span: Span::test_data(),
+                }),
             },
+            // Example {
+            //     description: "Sleep for 3sec",
+            //     example: "sleep 1sec 1sec 1sec",
+            //     result: None,
+            // },
+            // Example {
+            //     description: "Send output after 1sec",
+            //     example: "sleep 1sec; echo done",
+            //     result: None,
+            // },
         ]
     }
 }
diff --git a/crates/nu-command/src/strings/build_string.rs b/crates/nu-command/src/strings/build_string.rs
index b1ba80824a..085b9a3510 100644
--- a/crates/nu-command/src/strings/build_string.rs
+++ b/crates/nu-command/src/strings/build_string.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -25,6 +25,7 @@ impl Command for BuildString {
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("build-string")
             .rest("rest", SyntaxShape::String, "list of string")
+            .input_output_types(vec![(Type::Nothing, Type::String)])
             .category(Category::Strings)
     }
 
diff --git a/crates/nu-command/src/strings/char_.rs b/crates/nu-command/src/strings/char_.rs
index a56417a26d..be3b6944f7 100644
--- a/crates/nu-command/src/strings/char_.rs
+++ b/crates/nu-command/src/strings/char_.rs
@@ -4,7 +4,7 @@ use lazy_static::lazy_static;
 use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call, engine::Command, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData,
-    PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 // Character used to separate directories in a Path Environment variable on windows is ";"
@@ -156,6 +156,7 @@ impl Command for Char {
 
     fn signature(&self) -> Signature {
         Signature::build("char")
+            .input_output_types(vec![(Type::Nothing, Type::String)])
             .optional(
                 "character",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/strings/detect_columns.rs b/crates/nu-command/src/strings/detect_columns.rs
index 05ec5c9cd5..84230cc019 100644
--- a/crates/nu-command/src/strings/detect_columns.rs
+++ b/crates/nu-command/src/strings/detect_columns.rs
@@ -6,7 +6,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, SyntaxShape, Value,
+    Spanned, SyntaxShape, Type, Value,
 };
 
 type Input<'t> = Peekable<CharIndices<'t>>;
@@ -27,6 +27,7 @@ impl Command for DetectColumns {
                 "number of rows to skip before detecting",
                 Some('s'),
             )
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
             .switch("no-headers", "don't detect headers", Some('n'))
             .category(Category::Strings)
     }
diff --git a/crates/nu-command/src/strings/encode_decode/decode.rs b/crates/nu-command/src/strings/encode_decode/decode.rs
index 410108a91e..dea2185889 100644
--- a/crates/nu-command/src/strings/encode_decode/decode.rs
+++ b/crates/nu-command/src/strings/encode_decode/decode.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -24,6 +24,7 @@ impl Command for Decode {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("decode")
+            .input_output_types(vec![(Type::Binary, Type::String)])
             .required("encoding", SyntaxShape::String, "the text encoding to use")
             .category(Category::Strings)
     }
diff --git a/crates/nu-command/src/strings/encode_decode/decode_base64.rs b/crates/nu-command/src/strings/encode_decode/decode_base64.rs
index 3fbf39d5dd..d92989b148 100644
--- a/crates/nu-command/src/strings/encode_decode/decode_base64.rs
+++ b/crates/nu-command/src/strings/encode_decode/decode_base64.rs
@@ -2,7 +2,7 @@ use super::base64::{operate, ActionType, CHARACTER_SET_DESC};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,11 @@ impl Command for DecodeBase64 {
 
     fn signature(&self) -> Signature {
         Signature::build("decode base64")
+            .input_output_types(vec![
+                (Type::String, Type::String),
+                (Type::String, Type::Binary),
+            ])
+            .vectorizes_over_list(true)
             .named(
                 "character-set",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/strings/encode_decode/encode.rs b/crates/nu-command/src/strings/encode_decode/encode.rs
index e222361864..c112c7a550 100644
--- a/crates/nu-command/src/strings/encode_decode/encode.rs
+++ b/crates/nu-command/src/strings/encode_decode/encode.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -24,6 +24,7 @@ impl Command for Encode {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("encode")
+            .input_output_types(vec![(Type::String, Type::Binary)])
             .required("encoding", SyntaxShape::String, "the text encoding to use")
             .category(Category::Strings)
     }
diff --git a/crates/nu-command/src/strings/encode_decode/encode_base64.rs b/crates/nu-command/src/strings/encode_decode/encode_base64.rs
index 9b94a72242..44474ca938 100644
--- a/crates/nu-command/src/strings/encode_decode/encode_base64.rs
+++ b/crates/nu-command/src/strings/encode_decode/encode_base64.rs
@@ -15,6 +15,8 @@ impl Command for EncodeBase64 {
 
     fn signature(&self) -> Signature {
         Signature::build("encode base64")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .named(
                 "character-set",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/strings/format/command.rs b/crates/nu-command/src/strings/format/command.rs
index df72c095fc..2d88988ff4 100644
--- a/crates/nu-command/src/strings/format/command.rs
+++ b/crates/nu-command/src/strings/format/command.rs
@@ -2,9 +2,9 @@ use nu_engine::{eval_expression, CallExt};
 use nu_parser::parse_expression;
 use nu_protocol::ast::{Call, PathMember};
 use nu_protocol::engine::{Command, EngineState, Stack, StateWorkingSet};
-use nu_protocol::Type;
 use nu_protocol::{
-    Category, Example, ListStream, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, ListStream, PipelineData, ShellError, Signature, Span, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -17,6 +17,10 @@ impl Command for Format {
 
     fn signature(&self) -> Signature {
         Signature::build("format")
+            .input_output_types(vec![(
+                Type::Table(vec![]),
+                Type::List(Box::new(Type::String)),
+            )])
             .required(
                 "pattern",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/strings/format/filesize.rs b/crates/nu-command/src/strings/format/filesize.rs
index 26081d292f..71e52e6a45 100644
--- a/crates/nu-command/src/strings/format/filesize.rs
+++ b/crates/nu-command/src/strings/format/filesize.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::{Call, CellPath};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     format_filesize, Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 struct Arguments {
@@ -28,6 +28,7 @@ impl Command for FileSize {
 
     fn signature(&self) -> Signature {
         Signature::build("format filesize")
+            .input_output_types(vec![(Type::Filesize, Type::String)])
             .required(
                 "format value",
                 SyntaxShape::String,
@@ -36,7 +37,7 @@ impl Command for FileSize {
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
-                "optinally find and replace text by column paths",
+                "Optionally find and replace text by column paths",
             )
             .category(Category::Strings)
     }
@@ -78,19 +79,19 @@ impl Command for FileSize {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Convert the size row to KB",
+                description: "Convert the size column to KB",
                 example: "ls | format filesize KB size",
                 result: None,
             },
             Example {
-                description: "Convert the apparent row to B",
+                description: "Convert the apparent column to B",
                 example: "du | format filesize B apparent",
                 result: None,
             },
             Example {
                 description: "Convert the size data to MB",
                 example: "4Gb | format filesize MB",
-                result: None,
+                result: Some(Value::test_string("4000.0 MB")),
             },
         ]
     }
diff --git a/crates/nu-command/src/strings/parse.rs b/crates/nu-command/src/strings/parse.rs
index 077837fbb3..24ed13f191 100644
--- a/crates/nu-command/src/strings/parse.rs
+++ b/crates/nu-command/src/strings/parse.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, ListStream, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -30,6 +30,7 @@ impl Command for Parse {
                 SyntaxShape::String,
                 "the pattern to match. Eg) \"{foo}: {bar}\"",
             )
+            .input_output_types(vec![(Type::String, Type::Table(vec![]))])
             .switch("regex", "use full regex syntax for patterns", Some('r'))
             .category(Category::Strings)
     }
diff --git a/crates/nu-command/src/strings/size.rs b/crates/nu-command/src/strings/size.rs
index 16e288d266..0069e233ca 100644
--- a/crates/nu-command/src/strings/size.rs
+++ b/crates/nu-command/src/strings/size.rs
@@ -1,7 +1,7 @@
 use fancy_regex::Regex;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
 use std::collections::BTreeMap;
 use std::{fmt, str};
 use unicode_segmentation::UnicodeSegmentation;
@@ -18,7 +18,9 @@ impl Command for Size {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("size").category(Category::Strings)
+        Signature::build("size")
+            .category(Category::Strings)
+            .input_output_types(vec![(Type::String, Type::Record(vec![]))])
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/strings/split/chars.rs b/crates/nu-command/src/strings/split/chars.rs
index ef28229984..e2f82abe8a 100644
--- a/crates/nu-command/src/strings/split/chars.rs
+++ b/crates/nu-command/src/strings/split/chars.rs
@@ -1,7 +1,7 @@
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
 };
 
 #[derive(Clone)]
@@ -13,11 +13,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("split chars").category(Category::Strings)
+        Signature::build("split chars")
+            .input_output_types(vec![(Type::String, Type::List(Box::new(Type::String)))])
+            .vectorizes_over_list(true)
+            .category(Category::Strings)
     }
 
     fn usage(&self) -> &str {
-        "Split a string's characters into separate rows"
+        "Split a string into a list of characters"
     }
 
     fn search_terms(&self) -> Vec<&str> {
@@ -26,7 +29,7 @@ impl Command for SubCommand {
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "Split the string's characters into separate rows",
+            description: "Split the string into a list of characters",
             example: "'hello' | split chars",
             result: Some(Value::List {
                 vals: vec![
diff --git a/crates/nu-command/src/strings/split/column.rs b/crates/nu-command/src/strings/split/column.rs
index 0cd8b78eac..1038bcfc3a 100644
--- a/crates/nu-command/src/strings/split/column.rs
+++ b/crates/nu-command/src/strings/split/column.rs
@@ -2,7 +2,8 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +16,14 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("split column")
+            .input_output_types(vec![
+                (Type::String, Type::Table(vec![])),
+                (
+                    // TODO: no test coverage (is this behavior a bug or a feature?)
+                    Type::List(Box::new(Type::String)),
+                    Type::Table(vec![]),
+                ),
+            ])
             .required(
                 "separator",
                 SyntaxShape::String,
@@ -71,7 +80,7 @@ impl Command for SubCommand {
             },
             Example {
                 description: "Split a string into columns of char and remove the empty columns",
-                example: "echo 'abc' | split column -c ''",
+                example: "'abc' | split column -c ''",
                 result: Some(Value::List {
                     vals: vec![Value::Record {
                         cols: vec![
@@ -89,6 +98,25 @@ impl Command for SubCommand {
                     span: Span::test_data(),
                 }),
             },
+            Example {
+                description: "Split a list of strings into a table",
+                example: "['a-b' 'c-d'] | split column -",
+                result: Some(Value::List {
+                    vals: vec![
+                        Value::Record {
+                            cols: vec!["column1".to_string(), "column2".to_string()],
+                            vals: vec![Value::test_string("a"), Value::test_string("b")],
+                            span: Span::test_data(),
+                        },
+                        Value::Record {
+                            cols: vec!["column1".to_string(), "column2".to_string()],
+                            vals: vec![Value::test_string("c"), Value::test_string("d")],
+                            span: Span::test_data(),
+                        },
+                    ],
+                    span: Span::test_data(),
+                }),
+            },
         ]
     }
 }
@@ -161,15 +189,14 @@ fn split_column_helper(
     }
 }
 
-// #[cfg(test)]
-// mod tests {
-//     use super::ShellError;
-//     use super::SubCommand;
+#[cfg(test)]
+mod test {
+    use super::*;
 
-//     #[test]
-//     fn examples_work_as_expected() -> Result<(), ShellError> {
-//         use crate::examples::test as test_examples;
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
 
-//         test_examples(SubCommand {})
-//     }
-// }
+        test_examples(SubCommand {})
+    }
+}
diff --git a/crates/nu-command/src/strings/split/list.rs b/crates/nu-command/src/strings/split/list.rs
index a18fd5ac78..0e84b43c9f 100644
--- a/crates/nu-command/src/strings/split/list.rs
+++ b/crates/nu-command/src/strings/split/list.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, PipelineData, Signature, Span, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,10 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("split list")
+            .input_output_types(vec![(
+                Type::List(Box::new(Type::Any)),
+                Type::List(Box::new(Type::List(Box::new(Type::Any)))),
+            )])
             .required(
                 "separator",
                 SyntaxShape::Any,
@@ -128,3 +132,15 @@ fn split_list(
     }
     .into_pipeline_data())
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(SubCommand {})
+    }
+}
diff --git a/crates/nu-command/src/strings/split/row.rs b/crates/nu-command/src/strings/split/row.rs
index c19a8b6832..29838ce389 100644
--- a/crates/nu-command/src/strings/split/row.rs
+++ b/crates/nu-command/src/strings/split/row.rs
@@ -2,7 +2,8 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +16,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("split row")
+            .input_output_types(vec![(Type::String, Type::List(Box::new(Type::String)))])
+            .vectorizes_over_list(true)
             .required(
                 "separator",
                 SyntaxShape::String,
@@ -133,15 +136,14 @@ fn split_row_helper(
     }
 }
 
-// #[cfg(test)]
-// mod tests {
-//     use super::ShellError;
-//     use super::SubCommand;
+#[cfg(test)]
+mod test {
+    use super::*;
 
-//     #[test]
-//     fn examples_work_as_expected() -> Result<(), ShellError> {
-//         use crate::examples::test as test_examples;
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
 
-//         test_examples(SubCommand {})
-//     }
-// }
+        test_examples(SubCommand {})
+    }
+}
diff --git a/crates/nu-command/src/strings/split/words.rs b/crates/nu-command/src/strings/split/words.rs
index 5012dc6737..6439ba9bb0 100644
--- a/crates/nu-command/src/strings/split/words.rs
+++ b/crates/nu-command/src/strings/split/words.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("split words")
+            .input_output_types(vec![(Type::String, Type::List(Box::new(Type::String)))])
+            .vectorizes_over_list(true)
             .category(Category::Strings)
             // .switch(
             //     "ignore-hyphenated",
diff --git a/crates/nu-command/src/strings/str_/case/camel_case.rs b/crates/nu-command/src/strings/str_/case/camel_case.rs
index 162810655f..217f5b17f1 100644
--- a/crates/nu-command/src/strings/str_/case/camel_case.rs
+++ b/crates/nu-command/src/strings/str_/case/camel_case.rs
@@ -2,7 +2,7 @@ use inflector::cases::camelcase::to_camel_case;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 use crate::operate;
@@ -17,6 +17,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str camel-case")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/capitalize.rs b/crates/nu-command/src/strings/str_/case/capitalize.rs
index 88ddb00e75..d0506bfe83 100644
--- a/crates/nu-command/src/strings/str_/case/capitalize.rs
+++ b/crates/nu-command/src/strings/str_/case/capitalize.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -15,6 +15,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str capitalize")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/downcase.rs b/crates/nu-command/src/strings/str_/case/downcase.rs
index 3ec0c9c7ab..6307baa343 100644
--- a/crates/nu-command/src/strings/str_/case/downcase.rs
+++ b/crates/nu-command/src/strings/str_/case/downcase.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -15,6 +15,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str downcase")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/kebab_case.rs b/crates/nu-command/src/strings/str_/case/kebab_case.rs
index 475ecbd838..83d96aa0b0 100644
--- a/crates/nu-command/src/strings/str_/case/kebab_case.rs
+++ b/crates/nu-command/src/strings/str_/case/kebab_case.rs
@@ -2,7 +2,7 @@ use inflector::cases::kebabcase::to_kebab_case;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 use crate::operate;
@@ -17,6 +17,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str kebab-case")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/pascal_case.rs b/crates/nu-command/src/strings/str_/case/pascal_case.rs
index 464dd0a444..9256927a8f 100644
--- a/crates/nu-command/src/strings/str_/case/pascal_case.rs
+++ b/crates/nu-command/src/strings/str_/case/pascal_case.rs
@@ -2,7 +2,7 @@ use inflector::cases::pascalcase::to_pascal_case;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 use crate::operate;
@@ -17,6 +17,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str pascal-case")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/screaming_snake_case.rs b/crates/nu-command/src/strings/str_/case/screaming_snake_case.rs
index af25878781..32b88ed3d0 100644
--- a/crates/nu-command/src/strings/str_/case/screaming_snake_case.rs
+++ b/crates/nu-command/src/strings/str_/case/screaming_snake_case.rs
@@ -2,7 +2,7 @@ use inflector::cases::screamingsnakecase::to_screaming_snake_case;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 use crate::operate;
@@ -16,6 +16,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str screaming-snake-case")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/snake_case.rs b/crates/nu-command/src/strings/str_/case/snake_case.rs
index 0459790933..34f8781787 100644
--- a/crates/nu-command/src/strings/str_/case/snake_case.rs
+++ b/crates/nu-command/src/strings/str_/case/snake_case.rs
@@ -2,7 +2,7 @@ use inflector::cases::snakecase::to_snake_case;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 use crate::operate;
@@ -16,6 +16,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str snake-case")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/title_case.rs b/crates/nu-command/src/strings/str_/case/title_case.rs
index 39b574b805..61ba3cdeb2 100644
--- a/crates/nu-command/src/strings/str_/case/title_case.rs
+++ b/crates/nu-command/src/strings/str_/case/title_case.rs
@@ -2,7 +2,7 @@ use inflector::cases::titlecase::to_title_case;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 use crate::operate;
@@ -17,6 +17,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str title-case")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/case/upcase.rs b/crates/nu-command/src/strings/str_/case/upcase.rs
index 555783adc0..63b60c1f6e 100644
--- a/crates/nu-command/src/strings/str_/case/upcase.rs
+++ b/crates/nu-command/src/strings/str_/case/upcase.rs
@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -13,11 +13,14 @@ impl Command for SubCommand {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("str upcase").rest(
-            "rest",
-            SyntaxShape::CellPath,
-            "optionally upcase text by column paths",
-        )
+        Signature::build("str upcase")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
+            .rest(
+                "rest",
+                SyntaxShape::CellPath,
+                "optionally upcase text by column paths",
+            )
     }
 
     fn usage(&self) -> &str {
diff --git a/crates/nu-command/src/strings/str_/collect.rs b/crates/nu-command/src/strings/str_/collect.rs
index 8bedc748ac..f3ff8efa75 100644
--- a/crates/nu-command/src/strings/str_/collect.rs
+++ b/crates/nu-command/src/strings/str_/collect.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,7 @@ impl Command for StrCollect {
 
     fn signature(&self) -> Signature {
         Signature::build("str collect")
+            .input_output_types(vec![(Type::List(Box::new(Type::String)), Type::String)])
             .optional(
                 "separator",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/strings/str_/contains.rs b/crates/nu-command/src/strings/str_/contains.rs
index be972c7dd3..1da80c5dd8 100644
--- a/crates/nu-command/src/strings/str_/contains.rs
+++ b/crates/nu-command/src/strings/str_/contains.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -29,6 +29,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str contains")
+            .input_output_types(vec![(Type::String, Type::Bool)])
+            .vectorizes_over_list(true)
             .required("string", SyntaxShape::String, "the string to find")
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/strings/str_/distance.rs b/crates/nu-command/src/strings/str_/distance.rs
index 87075a67ed..c9ec679dbd 100644
--- a/crates/nu-command/src/strings/str_/distance.rs
+++ b/crates/nu-command/src/strings/str_/distance.rs
@@ -4,7 +4,7 @@ use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
     levenshtein_distance, Category, Example, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -28,6 +28,7 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str distance")
+            .input_output_types(vec![(Type::String, Type::Int)])
             .required(
                 "compare-string",
                 SyntaxShape::String,
@@ -42,11 +43,11 @@ impl Command for SubCommand {
     }
 
     fn usage(&self) -> &str {
-        "compare two strings and return the edit distance/levenshtein distance"
+        "Compare two strings and return the edit distance/Levenshtein distance"
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["edit", "match", "score", "levenshtein"]
+        vec!["edit", "levenshtein"]
     }
 
     fn run(
@@ -70,8 +71,19 @@ impl Command for SubCommand {
         vec![Example {
             description: "get the edit distance between two strings",
             example: "'nushell' | str distance 'nutshell'",
-            result: Some(Value::Int {
-                val: 1,
+            result: Some(Value::test_int(1)),
+        },
+        Example {
+            description: "Compute edit distance between strings in record and another string, using cell paths",
+            example: "[{a: 'nutshell' b: 'numetal'}] | str distance 'nushell' 'a' 'b'",
+            result: Some(Value::List {
+                vals: vec![
+                    Value::Record {
+                        cols: vec!["a".to_string(), "b".to_string()],
+                        vals: vec![Value::test_int(1), Value::test_int(4)],
+                        span: Span::test_data(),
+                    }
+                ],
                 span: Span::test_data(),
             }),
         }]
diff --git a/crates/nu-command/src/strings/str_/ends_with.rs b/crates/nu-command/src/strings/str_/ends_with.rs
index cf38b5a12c..dedb3aae38 100644
--- a/crates/nu-command/src/strings/str_/ends_with.rs
+++ b/crates/nu-command/src/strings/str_/ends_with.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     substring: String,
@@ -27,11 +27,13 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str ends-with")
+            .input_output_types(vec![(Type::String, Type::Bool)])
+            .vectorizes_over_list(true)
             .required("string", SyntaxShape::String, "the string to match")
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
-                "optionally matches suffix of text by column paths",
+                "optionally matches suffix of text by cell paths",
             )
             .category(Category::Strings)
     }
diff --git a/crates/nu-command/src/strings/str_/index_of.rs b/crates/nu-command/src/strings/str_/index_of.rs
index adfb003ede..e10953fd12 100644
--- a/crates/nu-command/src/strings/str_/index_of.rs
+++ b/crates/nu-command/src/strings/str_/index_of.rs
@@ -5,7 +5,7 @@ use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
 use nu_protocol::Spanned;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     end: bool,
@@ -33,6 +33,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str index-of")
+            .input_output_types(vec![(Type::String, Type::Int)])
+            .vectorizes_over_list(true) // TODO: no test coverage
             .required("string", SyntaxShape::String, "the string to find index of")
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/strings/str_/join.rs b/crates/nu-command/src/strings/str_/join.rs
index fe8f659514..350b2e6b17 100644
--- a/crates/nu-command/src/strings/str_/join.rs
+++ b/crates/nu-command/src/strings/str_/join.rs
@@ -3,7 +3,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
     Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Value,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -16,6 +16,7 @@ impl Command for StrJoin {
 
     fn signature(&self) -> Signature {
         Signature::build("str join")
+            .input_output_types(vec![(Type::List(Box::new(Type::String)), Type::String)])
             .optional(
                 "separator",
                 SyntaxShape::String,
diff --git a/crates/nu-command/src/strings/str_/length.rs b/crates/nu-command/src/strings/str_/length.rs
index 77c4afb30c..22cc715390 100644
--- a/crates/nu-command/src/strings/str_/length.rs
+++ b/crates/nu-command/src/strings/str_/length.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 #[derive(Clone)]
 pub struct SubCommand;
 
@@ -15,6 +15,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str length")
+            .input_output_types(vec![(Type::String, Type::Int)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/lpad.rs b/crates/nu-command/src/strings/str_/lpad.rs
index 386dc60531..c22221e8ee 100644
--- a/crates/nu-command/src/strings/str_/lpad.rs
+++ b/crates/nu-command/src/strings/str_/lpad.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     length: Option<i64>,
@@ -28,6 +28,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str lpad")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .required_named("length", SyntaxShape::Int, "length to pad to", Some('l'))
             .required_named(
                 "character",
diff --git a/crates/nu-command/src/strings/str_/replace.rs b/crates/nu-command/src/strings/str_/replace.rs
index eb594a6d13..60edfe3aba 100644
--- a/crates/nu-command/src/strings/str_/replace.rs
+++ b/crates/nu-command/src/strings/str_/replace.rs
@@ -4,7 +4,8 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
+    Value,
 };
 
 struct Arguments {
@@ -32,6 +33,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str replace")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .required("find", SyntaxShape::String, "the pattern to find")
             .required("replace", SyntaxShape::String, "the replacement pattern")
             .rest(
diff --git a/crates/nu-command/src/strings/str_/reverse.rs b/crates/nu-command/src/strings/str_/reverse.rs
index 6515f12858..8e8681dd14 100644
--- a/crates/nu-command/src/strings/str_/reverse.rs
+++ b/crates/nu-command/src/strings/str_/reverse.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -16,6 +16,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str reverse")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .rest(
                 "rest",
                 SyntaxShape::CellPath,
diff --git a/crates/nu-command/src/strings/str_/rpad.rs b/crates/nu-command/src/strings/str_/rpad.rs
index e513dc3262..b4b87c4f1c 100644
--- a/crates/nu-command/src/strings/str_/rpad.rs
+++ b/crates/nu-command/src/strings/str_/rpad.rs
@@ -4,7 +4,7 @@ use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     length: Option<i64>,
@@ -28,6 +28,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str rpad")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .required_named("length", SyntaxShape::Int, "length to pad to", Some('l'))
             .required_named(
                 "character",
diff --git a/crates/nu-command/src/strings/str_/starts_with.rs b/crates/nu-command/src/strings/str_/starts_with.rs
index 8445580a29..375401163f 100644
--- a/crates/nu-command/src/strings/str_/starts_with.rs
+++ b/crates/nu-command/src/strings/str_/starts_with.rs
@@ -5,7 +5,7 @@ use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::Category;
 use nu_protocol::Spanned;
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 
 struct Arguments {
     substring: String,
@@ -29,6 +29,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str starts-with")
+            .input_output_types(vec![(Type::String, Type::Bool)])
+            .vectorizes_over_list(true)
             .required("string", SyntaxShape::String, "the string to match")
             .rest(
                 "rest",
diff --git a/crates/nu-command/src/strings/str_/substring.rs b/crates/nu-command/src/strings/str_/substring.rs
index fb0c6243bd..6eb738c7a7 100644
--- a/crates/nu-command/src/strings/str_/substring.rs
+++ b/crates/nu-command/src/strings/str_/substring.rs
@@ -3,7 +3,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::ast::CellPath;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
 use std::cmp::Ordering;
 
 #[derive(Clone)]
@@ -38,6 +38,8 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str substring")
+            .input_output_types(vec![(Type::String, Type::String)])
+            .vectorizes_over_list(true)
             .required(
                 "range",
                 SyntaxShape::Any,
diff --git a/crates/nu-command/src/strings/str_/trim/trim_.rs b/crates/nu-command/src/strings/str_/trim/trim_.rs
index 8fc00abcfa..c38ed3cc0b 100644
--- a/crates/nu-command/src/strings/str_/trim/trim_.rs
+++ b/crates/nu-command/src/strings/str_/trim/trim_.rs
@@ -4,7 +4,7 @@ use nu_engine::CallExt;
 use nu_protocol::{
     ast::{Call, CellPath},
     engine::{Command, EngineState, Stack},
-    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Value,
+    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -39,7 +39,9 @@ impl Command for SubCommand {
 
     fn signature(&self) -> Signature {
         Signature::build("str trim")
-            .rest(
+        .input_output_types(vec![(Type::String, Type::String)])
+        .vectorizes_over_list(true)
+        .rest(
                 "rest",
                 SyntaxShape::CellPath,
                 "optionally trim text by column paths",
diff --git a/crates/nu-command/src/viewers/griddle.rs b/crates/nu-command/src/viewers/griddle.rs
index d85f1bebe1..83b4bb7829 100644
--- a/crates/nu-command/src/viewers/griddle.rs
+++ b/crates/nu-command/src/viewers/griddle.rs
@@ -7,7 +7,7 @@ use nu_protocol::{
     ast::{Call, PathMember},
     engine::{Command, EngineState, Stack},
     Category, Config, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span,
-    SyntaxShape, Value,
+    SyntaxShape, Type, Value,
 };
 use nu_term_grid::grid::{Alignment, Cell, Direction, Filling, Grid, GridOptions};
 use nu_utils::get_ls_colors;
@@ -26,6 +26,11 @@ impl Command for Griddle {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("grid")
+            .input_output_types(vec![
+                (Type::List(Box::new(Type::Any)), Type::String),
+                (Type::Record(vec![]), Type::String),
+                (Type::Table(vec![]), Type::String),
+            ])
             .named(
                 "width",
                 SyntaxShape::Int,
diff --git a/crates/nu-protocol/Cargo.toml b/crates/nu-protocol/Cargo.toml
index ca2e0d16e2..59a12f5ecf 100644
--- a/crates/nu-protocol/Cargo.toml
+++ b/crates/nu-protocol/Cargo.toml
@@ -22,6 +22,8 @@ miette = { version = "5.1.0", features = ["fancy-no-backtrace"] }
 num-format = "0.4.3"
 serde = {version = "1.0.130", features = ["derive"]}
 serde_json = { version = "1.0", optional = true }
+strum = "0.24"
+strum_macros = "0.24"
 sys-locale = "0.2.0"
 thiserror = "1.0.31"
 typetag = "0.1.8"
diff --git a/crates/nu-protocol/src/signature.rs b/crates/nu-protocol/src/signature.rs
index d3af329ecd..de2a0a084f 100644
--- a/crates/nu-protocol/src/signature.rs
+++ b/crates/nu-protocol/src/signature.rs
@@ -110,9 +110,12 @@ pub struct Signature {
     pub required_positional: Vec<PositionalArg>,
     pub optional_positional: Vec<PositionalArg>,
     pub rest_positional: Option<PositionalArg>,
+    pub vectorizes_over_list: bool,
     pub named: Vec<Flag>,
     pub input_type: Type,
     pub output_type: Type,
+    pub input_output_types: Vec<(Type, Type)>,
+    pub allow_variants_without_examples: bool,
     pub is_filter: bool,
     pub creates_scope: bool,
     // Signature category used to classify commands stored in the list of declarations
@@ -142,8 +145,11 @@ impl Signature {
             required_positional: vec![],
             optional_positional: vec![],
             rest_positional: None,
+            vectorizes_over_list: false,
             input_type: Type::Any,
             output_type: Type::Any,
+            input_output_types: vec![],
+            allow_variants_without_examples: false,
             named: vec![],
             is_filter: false,
             creates_scope: false,
@@ -255,6 +261,22 @@ impl Signature {
         self
     }
 
+    /// Is this command capable of operating on its input via cell paths?
+    pub fn operates_on_cell_paths(&self) -> bool {
+        self.required_positional
+            .iter()
+            .chain(self.rest_positional.iter())
+            .any(|pos| {
+                matches!(
+                    pos,
+                    PositionalArg {
+                        shape: SyntaxShape::CellPath,
+                        ..
+                    }
+                )
+            })
+    }
+
     /// Add an optional named flag argument to the signature
     pub fn named(
         mut self,
@@ -335,6 +357,17 @@ impl Signature {
         self
     }
 
+    pub fn vectorizes_over_list(mut self, vectorizes_over_list: bool) -> Signature {
+        self.vectorizes_over_list = vectorizes_over_list;
+        self
+    }
+
+    /// Set the input-output type signature variants of the command
+    pub fn input_output_types(mut self, input_output_types: Vec<(Type, Type)>) -> Signature {
+        self.input_output_types = input_output_types;
+        self
+    }
+
     /// Changes the signature category
     pub fn category(mut self, category: Category) -> Signature {
         self.category = category;
@@ -348,6 +381,12 @@ impl Signature {
         self
     }
 
+    // Is it allowed for the type signature to feature a variant that has no corresponding example?
+    pub fn allow_variants_without_examples(mut self, allow: bool) -> Signature {
+        self.allow_variants_without_examples = allow;
+        self
+    }
+
     pub fn call_signature(&self) -> String {
         let mut one_liner = String::new();
         one_liner.push_str(&self.name);
diff --git a/crates/nu-protocol/src/syntax_shape.rs b/crates/nu-protocol/src/syntax_shape.rs
index 74aaa071e4..4b9929e8b5 100644
--- a/crates/nu-protocol/src/syntax_shape.rs
+++ b/crates/nu-protocol/src/syntax_shape.rs
@@ -97,6 +97,9 @@ pub enum SyntaxShape {
 
     /// A custom shape with custom completion logic
     Custom(Box<SyntaxShape>, DeclId),
+
+    /// Nothing
+    Nothing,
 }
 
 impl SyntaxShape {
@@ -127,14 +130,15 @@ impl SyntaxShape {
             SyntaxShape::Number => Type::Number,
             SyntaxShape::Operator => Type::Any,
             SyntaxShape::Range => Type::Any,
-            SyntaxShape::Record => Type::Record(vec![]), // FIXME: Add actual record type
+            SyntaxShape::Record => Type::Record(vec![]), // FIXME: What role should fields play in the Record type?
             SyntaxShape::RowCondition => Type::Bool,
             SyntaxShape::Boolean => Type::Bool,
             SyntaxShape::Signature => Type::Signature,
             SyntaxShape::String => Type::String,
-            SyntaxShape::Table => Type::List(Box::new(Type::Any)), // FIXME: Tables should have better types
+            SyntaxShape::Table => Type::List(Box::new(Type::Any)), // FIXME:  What role should columns play in the Table type?
             SyntaxShape::VarWithOptType => Type::Any,
             SyntaxShape::Variable => Type::Any,
+            SyntaxShape::Nothing => Type::Any,
         }
     }
 }
@@ -174,6 +178,7 @@ impl Display for SyntaxShape {
             SyntaxShape::Boolean => write!(f, "bool"),
             SyntaxShape::Error => write!(f, "error"),
             SyntaxShape::Custom(x, _) => write!(f, "custom<{}>", x),
+            SyntaxShape::Nothing => write!(f, "nothing"),
         }
     }
 }
diff --git a/crates/nu-protocol/src/ty.rs b/crates/nu-protocol/src/ty.rs
index 382764e420..bd7cbb6f74 100644
--- a/crates/nu-protocol/src/ty.rs
+++ b/crates/nu-protocol/src/ty.rs
@@ -1,10 +1,11 @@
 use serde::{Deserialize, Serialize};
+use strum_macros::EnumIter;
 
 use std::fmt::Display;
 
 use crate::SyntaxShape;
 
-#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Hash)]
+#[derive(Clone, Debug, Default, EnumIter, PartialEq, Eq, Serialize, Deserialize, Hash)]
 pub enum Type {
     Int,
     Float,
@@ -18,6 +19,7 @@ pub enum Type {
     Filesize,
     List(Box<Type>),
     Number,
+    #[default]
     Nothing,
     Record(Vec<(String, Type)>),
     Table(Vec<(String, Type)>),
@@ -30,6 +32,39 @@ pub enum Type {
 }
 
 impl Type {
+    pub fn is_subtype(&self, other: &Type) -> bool {
+        match (self, other) {
+            (t, u) if t == u => true,
+            (Type::Float, Type::Number) => true,
+            (Type::Int, Type::Number) => true,
+            (_, Type::Any) => true,
+            (Type::List(t), Type::List(u)) if t.is_subtype(u) => true, // List is covariant
+
+            // TODO: Currently Record types specify their field types. If we are
+            // going to continue to do that, then it might make sense to define
+            // a "structural subtyping" whereby r1 is a subtype of r2 is the
+            // fields of r1 are a "subset" of the fields of r2 (names are a
+            // subset and agree on types). However, if we do that, then we need
+            // a way to specify the supertype of all Records. For now, we define
+            // any Record to be a subtype of any other Record. This allows
+            // Record(vec![]) to be used as an ad-hoc supertype of all Records
+            // in command signatures. This comment applies to Tables also, with
+            // "columns" in place of "fields".
+            (Type::Record(_), Type::Record(_)) => true,
+            (Type::Table(_), Type::Table(_)) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_numeric(&self) -> bool {
+        matches!(self, Type::Int | Type::Float | Type::Number)
+    }
+
+    /// Does this type represent a data structure containing values that can be addressed using 'cell paths'?
+    pub fn accepts_cell_paths(&self) -> bool {
+        matches!(self, Type::List(_) | Type::Record(_) | Type::Table(_))
+    }
+
     pub fn to_shape(&self) -> SyntaxShape {
         match self {
             Type::Int => SyntaxShape::Int,
@@ -44,7 +79,7 @@ impl Type {
             Type::Filesize => SyntaxShape::Filesize,
             Type::List(x) => SyntaxShape::List(Box::new(x.to_shape())),
             Type::Number => SyntaxShape::Number,
-            Type::Nothing => SyntaxShape::Any,
+            Type::Nothing => SyntaxShape::Nothing,
             Type::Record(_) => SyntaxShape::Record,
             Type::Table(_) => SyntaxShape::Table,
             Type::ListStream => SyntaxShape::List(Box::new(SyntaxShape::Any)),
@@ -100,3 +135,44 @@ impl Display for Type {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Type;
+    use strum::IntoEnumIterator;
+
+    mod subtype_relation {
+        use super::*;
+
+        #[test]
+        fn test_reflexivity() {
+            for ty in Type::iter() {
+                assert!(ty.is_subtype(&ty));
+            }
+        }
+
+        #[test]
+        fn test_any_is_top_type() {
+            for ty in Type::iter() {
+                assert!(ty.is_subtype(&Type::Any));
+            }
+        }
+
+        #[test]
+        fn test_number_supertype() {
+            assert!(Type::Int.is_subtype(&Type::Number));
+            assert!(Type::Float.is_subtype(&Type::Number));
+        }
+
+        #[test]
+        fn test_list_covariance() {
+            for ty1 in Type::iter() {
+                for ty2 in Type::iter() {
+                    let list_ty1 = Type::List(Box::new(ty1.clone()));
+                    let list_ty2 = Type::List(Box::new(ty2.clone()));
+                    assert_eq!(list_ty1.is_subtype(&list_ty2), ty1.is_subtype(&ty2));
+                }
+            }
+        }
+    }
+}
diff --git a/crates/nu-protocol/src/value/mod.rs b/crates/nu-protocol/src/value/mod.rs
index 5303cad8be..c9562cae89 100644
--- a/crates/nu-protocol/src/value/mod.rs
+++ b/crates/nu-protocol/src/value/mod.rs
@@ -399,7 +399,11 @@ impl Value {
                     match &ty {
                         Some(x) => {
                             if &val_ty != x {
-                                ty = Some(Type::Any)
+                                if x.is_numeric() && val_ty.is_numeric() {
+                                    ty = Some(Type::Number)
+                                } else {
+                                    ty = Some(Type::Any)
+                                }
                             }
                         }
                         None => ty = Some(val_ty),
@@ -3181,4 +3185,68 @@ mod tests {
             assert!(!one_column_with_empty_string_and_one_value_with_a_string.is_empty());
         }
     }
+
+    mod get_type {
+        use crate::Type;
+
+        use super::*;
+
+        #[test]
+        fn test_list() {
+            let list_of_ints = Value::List {
+                vals: vec![Value::Int {
+                    val: 0,
+                    span: Span::unknown(),
+                }],
+                span: Span::unknown(),
+            };
+            let list_of_floats = Value::List {
+                vals: vec![Value::Float {
+                    val: 0.0,
+                    span: Span::unknown(),
+                }],
+                span: Span::unknown(),
+            };
+            let list_of_ints_and_floats = Value::List {
+                vals: vec![
+                    Value::Int {
+                        val: 0,
+                        span: Span::unknown(),
+                    },
+                    Value::Float {
+                        val: 0.0,
+                        span: Span::unknown(),
+                    },
+                ],
+                span: Span::unknown(),
+            };
+            let list_of_ints_and_floats_and_bools = Value::List {
+                vals: vec![
+                    Value::Int {
+                        val: 0,
+                        span: Span::unknown(),
+                    },
+                    Value::Float {
+                        val: 0.0,
+                        span: Span::unknown(),
+                    },
+                    Value::Bool {
+                        val: false,
+                        span: Span::unknown(),
+                    },
+                ],
+                span: Span::unknown(),
+            };
+            assert_eq!(list_of_ints.get_type(), Type::List(Box::new(Type::Int)));
+            assert_eq!(list_of_floats.get_type(), Type::List(Box::new(Type::Float)));
+            assert_eq!(
+                list_of_ints_and_floats_and_bools.get_type(),
+                Type::List(Box::new(Type::Any))
+            );
+            assert_eq!(
+                list_of_ints_and_floats.get_type(),
+                Type::List(Box::new(Type::Number))
+            );
+        }
+    }
 }