made changes in tools

tools.py

@@ -43,7 +43,7 @@ def web_search(query: str) -> str:
     )
     return context if context else "No results found."
 
-llm = ChatOpenAI(model = "gpt-4")
+llm = ChatOpenAI(model = "gpt-3.5-turbo")
 tools = [add, subtract, divide, web_search]
 llm_with_tools = llm.bind_tools(tools, parallel_tool_calls = False)