Fix lint and type-checker issues

- Add 'cast' import to fix mypy type compatibility error
- Remove unused imports to fix lint warnings
- Add assertions to reproduction script to use agent variables
- All custom tool patterns now work correctly

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

tests/test_custom_tools.py

@@ -4,9 +4,8 @@ This addresses issue #3226 where custom tool registration was broken in CrewAI 0
 """
 
 import pytest
-from typing import Any
 from crewai import Agent
-from crewai.tools import BaseTool, tool, Tool
+from crewai.tools import BaseTool, tool
 
 
 class TestCustomToolPatterns: