reduce import time by 6x (#1396)

* reduce import by 6x

* fix linting

src/crewai/tools/agent_tools.py

@@ -1,4 +1,3 @@
-from langchain.tools import StructuredTool
 from crewai.agents.agent_builder.utilities.base_agent_tool import BaseAgentTools
 
 
@@ -6,6 +5,8 @@ class AgentTools(BaseAgentTools):
     """Default tools around agent delegation"""
 
     def tools(self):
+        from langchain.tools import StructuredTool
+
         coworkers = ", ".join([f"{agent.role}" for agent in self.agents])
         tools = [
             StructuredTool.from_function(

src/crewai/tools/cache_tools.py

@@ -1,4 +1,3 @@
-from langchain.tools import StructuredTool
 from pydantic import BaseModel, Field
 
 from crewai.agents.cache import CacheHandler
@@ -14,6 +13,8 @@ class CacheTools(BaseModel):
     )
 
     def tool(self):
+        from langchain.tools import StructuredTool
+
         return StructuredTool.from_function(
             func=self.hit_cache,
             name=self.name,