Fix CI issues: type-checker, lint errors (S101, RET504, B904)

- Add type ignore for create_model call to fix type-checker error
- Fix exception chaining (B904) by using 'from e' syntax
- Fix unnecessary assignment (RET504) by returning directly
- Add noqa comments for S101 assert detection in test file

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

src/crewai/tools/structured_tool.py

@@ -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,
@@ -274,8 +274,7 @@ class CrewStructuredTool:
         self._increment_usage_count()
 
         if inspect.iscoroutinefunction(self.func):
-            result = asyncio.run(self.func(**parsed_args, **kwargs))
-            return result
+            return asyncio.run(self.func(**parsed_args, **kwargs))
 
         try:
             result = self.func(**parsed_args, **kwargs)