Allow RunContext to not be documented when require_parameter_descriptions=True as it's not passed to the model anyway

pydantic_ai_slim/pydantic_ai/_pydantic.py

@@ -76,8 +76,15 @@ def function_schema(  # noqa: C901
     description, field_descriptions = doc_descriptions(function, sig, docstring_format=docstring_format)
 
     if require_parameter_descriptions:
-        if len(field_descriptions) != len(sig.parameters):
+        if takes_ctx:
+            parameters_without_ctx = set(
+                name for name in sig.parameters if not _is_call_ctx(sig.parameters[name].annotation)
+            )
+            missing_params = parameters_without_ctx - set(field_descriptions)
+        else:
             missing_params = set(sig.parameters) - set(field_descriptions)
+
+        if missing_params:
             errors.append(f'Missing parameter descriptions for {", ".join(missing_params)}')
 
     for index, (name, p) in enumerate(sig.parameters.items()):

tests/test_tools.py

@@ -785,6 +785,20 @@ def test_enforce_parameter_descriptions() -> None:
     assert all(err_part in error_reason for err_part in error_parts)
 
 
+def test_enforce_parameter_descriptions_noraise() -> None:
+    async def complete_parameter_descriptions_docstring(ctx: RunContext, foo: int) -> str:  # pragma: no cover
+        """Describes function ops, but missing ctx description and contains non-existent parameter description.
+
+        :param foo: The foo thing.
+        :param bar: The bar thing.
+        """
+        return f'{foo}'
+
+    agent = Agent(FunctionModel(get_json_schema))
+
+    agent.tool(require_parameter_descriptions=True)(complete_parameter_descriptions_docstring)
+
+
 def test_json_schema_required_parameters(set_event_loop: None):
     agent = Agent(FunctionModel(get_json_schema))