Fix remaining lint issues: N818, RET504, and S101 errors

- Rename ToolUsageLimitExceeded to ToolUsageLimitExceededError (N818)
- Remove unnecessary assignments before return statements (RET504)
- Add noqa S101 comments to all assert statements in test file
- Fix all remaining lint errors while preserving functionality

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

src/crewai/tools/structured_tool.py

@@ -16,7 +16,7 @@ if TYPE_CHECKING:
     from crewai.tools.base_tool import BaseTool
 
 
-class ToolUsageLimitExceeded(Exception):
+class ToolUsageLimitExceededError(Exception):
     """Exception raised when a tool has reached its maximum usage limit."""
 
     pass
@@ -164,7 +164,7 @@ 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]
 
     def _validate_function_signature(self) -> None:
         """Validate that the function signature matches the args schema."""
@@ -207,13 +207,13 @@ class CrewStructuredTool:
 
                 raw_args = json.loads(raw_args)
             except json.JSONDecodeError as e:
-                raise ValueError(f"Failed to parse arguments as JSON: {e}")
+                raise ValueError(f"Failed to parse arguments as JSON: {e}") from e
 
         try:
             validated_args = self.args_schema.model_validate(raw_args)
             return validated_args.model_dump()
         except Exception as e:
-            raise ValueError(f"Arguments validation failed: {e}")
+            raise ValueError(f"Arguments validation failed: {e}") from e
 
     async def ainvoke(
         self,
@@ -234,7 +234,7 @@ class CrewStructuredTool:
         parsed_args = self._parse_args(input)
 
         if self.has_reached_max_usage_count():
-            raise ToolUsageLimitExceeded(
+            raise ToolUsageLimitExceededError(
                 f"Tool '{self.name}' has reached its maximum usage limit of {self.max_usage_count}. You should not use the {self.name} tool again."
             )
 
@@ -267,23 +267,20 @@ class CrewStructuredTool:
         parsed_args = self._parse_args(input)
 
         if self.has_reached_max_usage_count():
-            raise ToolUsageLimitExceeded(
+            raise ToolUsageLimitExceededError(
                 f"Tool '{self.name}' has reached its maximum usage limit of {self.max_usage_count}. You should not use the {self.name} tool again."
             )
 
         self._increment_usage_count()
 
         if inspect.iscoroutinefunction(self.func):
-            result = asyncio.run(self.func(**parsed_args, **kwargs))
+            return asyncio.run(self.func(**parsed_args, **kwargs))
-            return result
 
         try:
             result = self.func(**parsed_args, **kwargs)
         except Exception:
             raise
 
-        result = self.func(**parsed_args, **kwargs)
-
         if asyncio.iscoroutine(result):
             return asyncio.run(result)
 

tests/tools/test_structured_tool.py

@@ -34,10 +34,10 @@ def test_initialization(basic_function, schema_class):
         args_schema=schema_class,
     )
 
-    assert tool.name == "test_tool"
+    assert tool.name == "test_tool"  # noqa: S101
-    assert tool.description == "Test tool description"
+    assert tool.description == "Test tool description"  # noqa: S101
-    assert tool.func == basic_function
+    assert tool.func == basic_function  # noqa: S101
-    assert tool.args_schema == schema_class
+    assert tool.args_schema == schema_class  # noqa: S101
 
 def test_from_function(basic_function):
     """Test creating tool from function"""
@@ -45,10 +45,10 @@ def test_from_function(basic_function):
         func=basic_function, name="test_tool", description="Test description"
     )
 
-    assert tool.name == "test_tool"
+    assert tool.name == "test_tool"  # noqa: S101
-    assert tool.description == "Test description"
+    assert tool.description == "Test description"  # noqa: S101
-    assert tool.func == basic_function
+    assert tool.func == basic_function  # noqa: S101
-    assert isinstance(tool.args_schema, type(BaseModel))
+    assert isinstance(tool.args_schema, type(BaseModel))  # noqa: S101
 
 def test_validate_function_signature(basic_function, schema_class):
     """Test function signature validation"""
@@ -68,23 +68,23 @@ async def test_ainvoke(basic_function):
     tool = CrewStructuredTool.from_function(func=basic_function, name="test_tool")
 
     result = await tool.ainvoke(input={"param1": "test"})
-    assert result == "test 0"
+    assert result == "test 0"  # noqa: S101
 
 def test_parse_args_dict(basic_function):
     """Test parsing dictionary arguments"""
     tool = CrewStructuredTool.from_function(func=basic_function, name="test_tool")
 
     parsed = tool._parse_args({"param1": "test", "param2": 42})
-    assert parsed["param1"] == "test"
+    assert parsed["param1"] == "test"  # noqa: S101
-    assert parsed["param2"] == 42
+    assert parsed["param2"] == 42  # noqa: S101
 
 def test_parse_args_string(basic_function):
     """Test parsing string arguments"""
     tool = CrewStructuredTool.from_function(func=basic_function, name="test_tool")
 
     parsed = tool._parse_args('{"param1": "test", "param2": 42}')
-    assert parsed["param1"] == "test"
+    assert parsed["param1"] == "test"  # noqa: S101
-    assert parsed["param2"] == 42
+    assert parsed["param2"] == 42  # noqa: S101
 
 def test_complex_types():
     """Test handling of complex parameter types"""
@@ -97,7 +97,7 @@ def test_complex_types():
         func=complex_func, name="test_tool", description="Test complex types"
     )
     result = tool.invoke({"nested": {"key": "value"}, "items": [1, 2, 3]})
-    assert result == "Processed 3 items with 1 nested keys"
+    assert result == "Processed 3 items with 1 nested keys"  # noqa: S101
 
 def test_schema_inheritance():
     """Test tool creation with inherited schema"""
@@ -117,7 +117,7 @@ def test_schema_inheritance():
     )
 
     result = tool.invoke({"base_param": "test", "extra_param": 42})
-    assert result == "test 42"
+    assert result == "test 42"  # noqa: S101
 
 def test_default_values_in_schema():
     """Test handling of default values in schema"""
@@ -136,13 +136,39 @@ def test_default_values_in_schema():
 
     # Test with minimal parameters
     result = tool.invoke({"required_param": "test"})
-    assert result == "test default None"
+    assert result == "test default None"  # noqa: S101
 
     # Test with all parameters
     result = tool.invoke(
         {"required_param": "test", "optional_param": "custom", "nullable_param": 42}
     )
-    assert result == "test custom 42"
+    assert result == "test custom 42"  # noqa: S101
+
+
+def test_tool_not_executed_twice():
+    """Test that tool function is only executed once per invoke call (bug #3489)"""
+    call_count = 0
+    
+    def counting_func(param: str) -> str:
+        """Function that counts how many times it's called."""
+        nonlocal call_count
+        call_count += 1
+        return f"Called {call_count} times with {param}"
+    
+    tool = CrewStructuredTool.from_function(
+        func=counting_func, name="counting_tool", description="Counts calls"
+    )
+    
+    call_count = 0
+    
+    result = tool.invoke({"param": "test"})
+    
+    assert call_count == 1, f"Expected function to be called once, but was called {call_count} times"  # noqa: S101
+    assert result == "Called 1 times with test"  # noqa: S101
+    
+    result = tool.invoke({"param": "test2"})
+    assert call_count == 2, f"Expected function to be called twice total, but was called {call_count} times"  # noqa: S101
+    assert result == "Called 2 times with test2"  # noqa: S101
 
 @pytest.fixture
 def custom_tool_decorator():
@@ -178,22 +204,21 @@ def build_simple_crew(tool):
         description="Use the custom tool result as answer.", agent=agent1, expected_output="Use the tool result"
     )
 
-    crew = Crew(agents=[agent1], tasks=[say_hi_task])
+    return Crew(agents=[agent1], tasks=[say_hi_task])
-    return crew
 
 @pytest.mark.vcr(filter_headers=["authorization"])
 def test_async_tool_using_within_isolated_crew(custom_tool):
     crew = build_simple_crew(custom_tool)
     result = crew.kickoff()
 
-    assert result.raw == "Hello World from Custom Tool"
+    assert result.raw == "Hello World from Custom Tool"  # noqa: S101
 
 @pytest.mark.vcr(filter_headers=["authorization"])
 def test_async_tool_using_decorator_within_isolated_crew(custom_tool_decorator):
     crew = build_simple_crew(custom_tool_decorator)
     result = crew.kickoff()
 
-    assert result.raw == "Hello World from Custom Tool"
+    assert result.raw == "Hello World from Custom Tool"  # noqa: S101
 
 @pytest.mark.vcr(filter_headers=["authorization"])
 def test_async_tool_within_flow(custom_tool):
@@ -205,12 +230,11 @@ def test_async_tool_within_flow(custom_tool):
         @start()
         async def start(self):
             crew = build_simple_crew(custom_tool)
-            result = await crew.kickoff_async()
+            return await crew.kickoff_async()
-            return result
 
     flow = StructuredExampleFlow()
     result = flow.kickoff()
-    assert result.raw == "Hello World from Custom Tool"
+    assert result.raw == "Hello World from Custom Tool"  # noqa: S101
 
 
 @pytest.mark.vcr(filter_headers=["authorization"])
@@ -222,9 +246,8 @@ def test_async_tool_using_decorator_within_flow(custom_tool_decorator):
         @start()
         async def start(self):
             crew = build_simple_crew(custom_tool_decorator)
-            result = await crew.kickoff_async()
+            return await crew.kickoff_async()
-            return result
 
     flow = StructuredExampleFlow()
     result = flow.kickoff()
-    assert result.raw == "Hello World from Custom Tool"
+    assert result.raw == "Hello World from Custom Tool"  # noqa: S101