diff --git a/tests/test_cli.py b/tests/test_cli.py
index 6edff78f..3736f5bd 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -1,8 +1,9 @@
 import inspect
-from typing import Annotated
+from typing import Annotated, get_args
 
 import pytest
 import typer
+from typer.models import ArgumentInfo, OptionInfo
 from typer.testing import CliRunner
 
 from qcore import cli
@@ -137,3 +138,166 @@ def implicit_command(
     result = runner.invoke(app, ["5", "--param2", "z"])
     assert result.exit_code == 0
     assert result.stdout.strip() == "Implicit 5 z"
+
+
+def test_from_docstring_implicit_signature() -> None:
+    """Check the rewritten signature for implicit arguments and options."""
+
+    app = typer.Typer()
+
+    @cli.from_docstring(app)
+    def command(
+        documented: int,
+        undocumented,  # noqa: ANN001
+        opt: float = 1.5,
+        undoc_opt=2,  # noqa: ANN001
+    ) -> None:
+        """Summary.
+
+        Parameters
+        ----------
+        documented : int
+            Documented argument.
+        opt : float
+            Documented option.
+        """
+
+    params = inspect.signature(command).parameters
+
+    documented = params["documented"]
+    assert isinstance(documented.default, ArgumentInfo)
+    assert documented.default.default is ...
+    assert documented.default.help == "Documented argument."
+    assert documented.annotation is int
+
+    undocumented = params["undocumented"]
+    assert isinstance(undocumented.default, ArgumentInfo)
+    assert undocumented.default.help == ""
+    assert undocumented.annotation is str
+
+    opt = params["opt"]
+    assert isinstance(opt.default, OptionInfo)
+    assert opt.default.default == 1.5
+    assert opt.default.help == "Documented option."
+    assert opt.annotation is float
+
+    undoc_opt = params["undoc_opt"]
+    assert isinstance(undoc_opt.default, OptionInfo)
+    assert undoc_opt.default.default == 2
+    assert undoc_opt.default.help == ""
+    assert undoc_opt.annotation is str
+
+
+def test_from_docstring_implicit_runtime_behaviour() -> None:
+    """Required arguments are required and option defaults are kept."""
+
+    app = typer.Typer()
+
+    @cli.from_docstring(app)
+    def command(value: int, scale: float = 1.5) -> None:
+        """Summary."""
+        print(type(value).__name__, value, scale)
+
+    result = runner.invoke(app, [])
+    assert result.exit_code != 0
+
+    result = runner.invoke(app, ["3"])
+    assert result.exit_code == 0
+    assert result.stdout.strip() == "int 3 1.5"
+
+
+def test_from_docstring_keeps_explicit_annotated_help() -> None:
+    """Explicit help in Annotated metadata is not overwritten by the docstring."""
+
+    app = typer.Typer()
+
+    @cli.from_docstring(app)
+    def command(
+        explicit: Annotated[int, typer.Argument(help="Explicit help.")],
+        implicit: Annotated[int, typer.Option()] = 1,
+    ) -> None:
+        """Summary.
+
+        Parameters
+        ----------
+        explicit : int
+            Docstring help.
+        implicit : int
+            Implicit help.
+        """
+
+    params = inspect.signature(command).parameters
+    (explicit_info,) = get_args(params["explicit"].annotation)[1:]
+    assert explicit_info.help == "Explicit help."
+    (implicit_info,) = get_args(params["implicit"].annotation)[1:]
+    assert implicit_info.help == "Implicit help."
+
+
+def test_from_docstring_command_help_short_only() -> None:
+    """A docstring without a long description yields just the summary."""
+
+    app = typer.Typer()
+
+    @cli.from_docstring(app)
+    def command() -> None:
+        """Summary only."""
+
+    assert app.registered_commands[0].help == "Summary only."
+
+
+def test_from_docstring_command_help_with_long_description() -> None:
+    """The long description is appended to the summary."""
+
+    app = typer.Typer()
+
+    @cli.from_docstring(app)
+    def command() -> None:
+        """Summary.
+
+        Longer description.
+        """
+
+    assert app.registered_commands[0].help == "Summary.\n\nLonger description."
+
+
+def test_from_docstring_command_help_no_summary() -> None:
+    """A docstring with only a parameters section gives empty command help."""
+
+    app = typer.Typer()
+
+    @cli.from_docstring(app)
+    def command(x: int) -> None:
+        """
+        Parameters
+        ----------
+        x : int
+            X help.
+        """
+
+    assert app.registered_commands[0].help == ""
+    x = inspect.signature(command).parameters["x"]
+    assert isinstance(x.default, ArgumentInfo)
+    assert x.default.help == "X help."
+
+
+def test_from_docstring_forces_numpydoc_style() -> None:
+    """The docstring is parsed as numpydoc even if another style has more fields."""
+
+    app = typer.Typer()
+
+    @cli.from_docstring(app)
+    def command(x: int) -> None:
+        """Summary.
+
+        :param a: Not a numpydoc parameter.
+        :param b: Not a numpydoc parameter.
+
+        Parameters
+        ----------
+        x : int
+            X help.
+        """
+
+    x = inspect.signature(command).parameters["x"]
+    assert isinstance(x.default, ArgumentInfo)
+    assert x.default.help == "X help."