Fix type-checking errors in structured_tool.py and tests

- Add comprehensive type annotations for all function parameters and return types
- Fix generic type parameters for dict, Callable, and Flow classes
- Add proper type ignore comments for complex type inference scenarios
- Resolve all 27 mypy errors across Python 3.10-3.13
- Ensure compatibility with strict type checking requirements

Co-Authored-By: João <joao@crewai.com>

src/crewai/tools/structured_tool.py

@@ -66,7 +66,7 @@ class CrewStructuredTool:
     @classmethod
     def from_function(
         cls,
-        func: Callable,
+        func: Callable[..., Any],
         name: Optional[str] = None,
         description: Optional[str] = None,
         return_direct: bool = False,
@@ -127,7 +127,7 @@ class CrewStructuredTool:
     @staticmethod
     def _create_schema_from_function(
         name: str,
-        func: Callable,
+        func: Callable[..., Any],
     ) -> type[BaseModel]:
         """Create a Pydantic schema from a function's signature.
 
@@ -162,7 +162,7 @@ class CrewStructuredTool:
 
         # Create model
         schema_name = f"{name.title()}Schema"
-        return create_model(schema_name, **fields)
+        return create_model(schema_name, **fields)  # type: ignore[call-overload,no-any-return]
 
     def _validate_function_signature(self) -> None:
         """Validate that the function signature matches the args schema."""
@@ -190,7 +190,7 @@ class CrewStructuredTool:
                         f"not found in args_schema"
                     )
 
-    def _parse_args(self, raw_args: str | dict) -> dict:
+    def _parse_args(self, raw_args: str | dict[str, Any]) -> dict[str, Any]:
         """Parse and validate the input arguments against the schema.
 
         Args:
@@ -215,8 +215,8 @@ class CrewStructuredTool:
 
     async def ainvoke(
         self,
-        input: str | dict,
+        input: str | dict[str, Any],
-        config: Optional[dict] = None,
+        config: Optional[dict[str, Any]] = None,
         **kwargs: Any,
     ) -> Any:
         """Asynchronously invoke the tool.
@@ -251,7 +251,7 @@ class CrewStructuredTool:
         except Exception:
             raise
 
-    def _run(self, *args, **kwargs) -> Any:
+    def _run(self, *args: Any, **kwargs: Any) -> Any:
         """Legacy method for compatibility."""
         # Convert args/kwargs to our expected format
         input_dict = dict(zip(self.args_schema.model_fields.keys(), args))
@@ -259,7 +259,10 @@ class CrewStructuredTool:
         return self.invoke(input_dict)
 
     def invoke(
-        self, input: str | dict, config: Optional[dict] = None, **kwargs: Any
+        self,
+        input: str | dict[str, Any],
+        config: Optional[dict[str, Any]] = None,
+        **kwargs: Any,
     ) -> Any:
         """Main method for tool execution."""
         parsed_args = self._parse_args(input)
@@ -319,9 +322,9 @@ class CrewStructuredTool:
             self._original_tool.current_usage_count = self.current_usage_count
 
     @property
-    def args(self) -> dict:
+    def args(self) -> dict[str, Any]:
         """Get the tool's input arguments schema."""
-        return self.args_schema.model_json_schema()["properties"]
+        return self.args_schema.model_json_schema()["properties"]  # type: ignore[no-any-return]
 
     def __repr__(self) -> str:
         return (

tests/tools/test_structured_tool.py

@@ -1,14 +1,16 @@
-from typing import Optional
+from collections.abc import Callable
+from typing import Any, Optional
 
 import pytest
 from pydantic import BaseModel, Field
 
+from crewai.tools import BaseTool
 from crewai.tools.structured_tool import CrewStructuredTool
 
 
 # Test fixtures
 @pytest.fixture
-def basic_function():
+def basic_function() -> Callable[[str, int], str]:
     def test_func(param1: str, param2: int = 0) -> str:
         """Test function with basic params."""
         return f"{param1} {param2}"
@@ -17,7 +19,7 @@ def basic_function():
 
 
 @pytest.fixture
-def schema_class():
+def schema_class() -> type[BaseModel]:
     class TestSchema(BaseModel):
         param1: str
         param2: int = Field(default=0)
@@ -25,7 +27,9 @@ def schema_class():
     return TestSchema
 
 
-def test_initialization(basic_function, schema_class):
+def test_initialization(
+    basic_function: Callable[[str], str], schema_class: type[BaseModel]
+) -> None:
     """Test basic initialization of CrewStructuredTool"""
     tool = CrewStructuredTool(
         name="test_tool",
@@ -40,7 +44,7 @@ def test_initialization(basic_function, schema_class):
     assert tool.args_schema == schema_class
 
 
-def test_from_function(basic_function):
+def test_from_function(basic_function: Callable[[str], str]) -> None:
     """Test creating tool from function"""
     tool = CrewStructuredTool.from_function(
         func=basic_function, name="test_tool", description="Test description"
@@ -52,7 +56,9 @@ def test_from_function(basic_function):
     assert isinstance(tool.args_schema, type(BaseModel))
 
 
-def test_validate_function_signature(basic_function, schema_class):
+def test_validate_function_signature(
+    basic_function: Callable[[str, int], str], schema_class: type[BaseModel]
+) -> None:
     """Test function signature validation"""
     tool = CrewStructuredTool(
         name="test_tool",
@@ -66,7 +72,7 @@ def test_validate_function_signature(basic_function, schema_class):
 
 
 @pytest.mark.asyncio
-async def test_ainvoke(basic_function):
+async def test_ainvoke(basic_function: Callable[[str, int], str]) -> None:
     """Test asynchronous invocation"""
     tool = CrewStructuredTool.from_function(func=basic_function, name="test_tool")
 
@@ -74,7 +80,7 @@ async def test_ainvoke(basic_function):
     assert result == "test 0"
 
 
-def test_parse_args_dict(basic_function):
+def test_parse_args_dict(basic_function: Callable[[str, int], str]) -> None:
     """Test parsing dictionary arguments"""
     tool = CrewStructuredTool.from_function(func=basic_function, name="test_tool")
 
@@ -83,7 +89,7 @@ def test_parse_args_dict(basic_function):
     assert parsed["param2"] == 42
 
 
-def test_parse_args_string(basic_function):
+def test_parse_args_string(basic_function: Callable[[str, int], str]) -> None:
     """Test parsing string arguments"""
     tool = CrewStructuredTool.from_function(func=basic_function, name="test_tool")
 
@@ -92,10 +98,10 @@ def test_parse_args_string(basic_function):
     assert parsed["param2"] == 42
 
 
-def test_complex_types():
+def test_complex_types() -> None:
     """Test handling of complex parameter types"""
 
-    def complex_func(nested: dict, items: list) -> str:
+    def complex_func(nested: dict[str, Any], items: list[Any]) -> str:
         """Process complex types."""
         return f"Processed {len(items)} items with {len(nested)} nested keys"
 
@@ -106,7 +112,7 @@ def test_complex_types():
     assert result == "Processed 3 items with 1 nested keys"
 
 
-def test_schema_inheritance():
+def test_schema_inheritance() -> None:
     """Test tool creation with inherited schema"""
 
     def extended_func(base_param: str, extra_param: int) -> str:
@@ -127,7 +133,7 @@ def test_schema_inheritance():
     assert result == "test 42"
 
 
-def test_default_values_in_schema():
+def test_default_values_in_schema() -> None:
     """Test handling of default values in schema"""
 
     def default_func(
@@ -154,11 +160,11 @@ def test_default_values_in_schema():
 
 
 @pytest.fixture
-def custom_tool_decorator():
+def custom_tool_decorator() -> Any:
     from crewai.tools import tool
 
     @tool("custom_tool", result_as_answer=True)
-    async def custom_tool():
+    async def custom_tool() -> str:
         """This is a tool that does something"""
         return "Hello World from Custom Tool"
 
@@ -166,7 +172,7 @@ def custom_tool_decorator():
 
 
 @pytest.fixture
-def custom_tool():
+def custom_tool() -> BaseTool:
     from crewai.tools import BaseTool
 
     class CustomTool(BaseTool):
@@ -174,13 +180,13 @@ def custom_tool():
         description: str = "This is a tool that does something"
         result_as_answer: bool = True
 
-        async def _run(self):
+        async def _run(self) -> str:
             return "Hello World from Custom Tool"
 
     return CustomTool()
 
 
-def build_simple_crew(tool):
+def build_simple_crew(tool: Any) -> Any:
     from crewai import Agent, Crew, Task
 
     agent1 = Agent(
@@ -201,7 +207,7 @@ def build_simple_crew(tool):
 
 
 @pytest.mark.vcr(filter_headers=["authorization"])
-def test_async_tool_using_within_isolated_crew(custom_tool):
+def test_async_tool_using_within_isolated_crew(custom_tool: BaseTool) -> None:
     crew = build_simple_crew(custom_tool)
     result = crew.kickoff()
 
@@ -209,7 +215,9 @@ def test_async_tool_using_within_isolated_crew(custom_tool):
 
 
 @pytest.mark.vcr(filter_headers=["authorization"])
-def test_async_tool_using_decorator_within_isolated_crew(custom_tool_decorator):
+def test_async_tool_using_decorator_within_isolated_crew(
+    custom_tool_decorator: Any,
+) -> None:
     crew = build_simple_crew(custom_tool_decorator)
     result = crew.kickoff()
 
@@ -217,14 +225,12 @@ def test_async_tool_using_decorator_within_isolated_crew(custom_tool_decorator):
 
 
 @pytest.mark.vcr(filter_headers=["authorization"])
-def test_async_tool_within_flow(custom_tool):
+def test_async_tool_within_flow(custom_tool: BaseTool) -> None:
-    from crewai.flow.flow import Flow
+    from crewai.flow.flow import Flow, start
-
-    class StructuredExampleFlow(Flow):
-        from crewai.flow.flow import start
 
+    class StructuredExampleFlow(Flow):  # type: ignore[type-arg]
         @start()
-        async def start(self):
+        async def start(self) -> Any:
             crew = build_simple_crew(custom_tool)
             result = await crew.kickoff_async()
             return result
@@ -235,14 +241,12 @@ def test_async_tool_within_flow(custom_tool):
 
 
 @pytest.mark.vcr(filter_headers=["authorization"])
-def test_async_tool_using_decorator_within_flow(custom_tool_decorator):
+def test_async_tool_using_decorator_within_flow(custom_tool_decorator: Any) -> None:
-    from crewai.flow.flow import Flow
+    from crewai.flow.flow import Flow, start
-
-    class StructuredExampleFlow(Flow):
-        from crewai.flow.flow import start
 
+    class StructuredExampleFlow(Flow):  # type: ignore[type-arg]
         @start()
-        async def start(self):
+        async def start(self) -> Any:
             crew = build_simple_crew(custom_tool_decorator)
             result = await crew.kickoff_async()
             return result
@@ -252,7 +256,7 @@ def test_async_tool_using_decorator_within_flow(custom_tool_decorator):
     assert result.raw == "Hello World from Custom Tool"
 
 
-def test_invoke_sync_function_single_execution():
+def test_invoke_sync_function_single_execution() -> None:
     """Test that sync functions are called only once, not twice."""
     call_count = 0
 
@@ -270,7 +274,7 @@ def test_invoke_sync_function_single_execution():
     assert result == "Called 1 times with: test"
 
 
-def test_invoke_async_function_outside_event_loop():
+def test_invoke_async_function_outside_event_loop() -> None:
     """Test that async functions work correctly when called outside event loop."""
 
     async def async_func(message: str) -> str:
@@ -285,7 +289,7 @@ def test_invoke_async_function_outside_event_loop():
 
 
 @pytest.mark.asyncio
-async def test_invoke_async_function_in_event_loop_raises_error():
+async def test_invoke_async_function_in_event_loop_raises_error() -> None:
     """Test that async functions raise RuntimeError when called from within event loop."""
 
     async def async_func(message: str) -> str:
@@ -302,13 +306,13 @@ async def test_invoke_async_function_in_event_loop_raises_error():
         tool.invoke({"message": "test"})
 
 
-def test_invoke_sync_function_returning_coroutine():
+def test_invoke_sync_function_returning_coroutine() -> None:
     """Test handling of sync functions that return coroutines."""
 
     async def inner_async(message: str) -> str:
         return f"Inner async: {message}"
 
-    def sync_func_returning_coro(message: str):
+    def sync_func_returning_coro(message: str) -> Any:
         return inner_async(message)
 
     tool = CrewStructuredTool.from_function(
@@ -322,13 +326,15 @@ def test_invoke_sync_function_returning_coroutine():
 
 
 @pytest.mark.asyncio
-async def test_invoke_sync_function_returning_coroutine_in_event_loop_raises_error():
+async def test_invoke_sync_function_returning_coroutine_in_event_loop_raises_error() -> (
+    None
+):
     """Test that sync functions returning coroutines raise RuntimeError in event loop."""
 
     async def inner_async(message: str) -> str:
         return f"Inner async: {message}"
 
-    def sync_func_returning_coro(message: str):
+    def sync_func_returning_coro(message: str) -> Any:
         return inner_async(message)
 
     tool = CrewStructuredTool.from_function(