Update using langchain tools docs (#1664)

* Update example of how to use LangChain tools with correct syntax

* Use .env

* Add  Code back

---------

Co-authored-by: Brandon Hancock (bhancock_ai) <[email protected]>

docs/concepts/langchain-tools.mdx

@@ -7,39 +7,52 @@ icon: link
 ## Using LangChain Tools
 
 <Info>
-    CrewAI seamlessly integrates with LangChain’s comprehensive [list of tools](https://python.langchain.com/docs/integrations/tools/), all of which can be used with CrewAI.
+    CrewAI seamlessly integrates with LangChain's comprehensive [list of tools](https://python.langchain.com/docs/integrations/tools/), all of which can be used with CrewAI.
 </Info>
 
 ```python Code
 import os
-from crewai import Agent
-from langchain.agents import Tool
-from langchain.utilities import GoogleSerperAPIWrapper
+from dotenv import load_dotenv
+from crewai import Agent, Task, Crew
+from crewai.tools import BaseTool
+from pydantic import Field
+from langchain_community.utilities import GoogleSerperAPIWrapper
 
-# Setup API keys
-os.environ["SERPER_API_KEY"] = "Your Key"
+# Set up your SERPER_API_KEY key in an .env file, eg:
+# SERPER_API_KEY=<your api key>
+load_dotenv()
 
 search = GoogleSerperAPIWrapper()
 
-# Create and assign the search tool to an agent
-serper_tool = Tool(
-  name="Intermediate Answer",
-  func=search.run,
-  description="Useful for search-based queries",
-)
-
-agent = Agent(
-  role='Research Analyst',
-  goal='Provide up-to-date market analysis',
-  backstory='An expert analyst with a keen eye for market trends.',
-  tools=[serper_tool]
+class SearchTool(BaseTool):
+    name: str = "Search"
+    description: str = "Useful for search-based queries. Use this to find current information about markets, companies, and trends."
+    search: GoogleSerperAPIWrapper = Field(default_factory=GoogleSerperAPIWrapper)
+
+    def _run(self, query: str) -> str:
+        """Execute the search query and return results"""
+        try:
+            return self.search.run(query)
+        except Exception as e:
+            return f"Error performing search: {str(e)}"
+
+# Create Agents
+researcher = Agent(
+    role='Research Analyst',
+    goal='Gather current market data and trends',
+    backstory="""You are an expert research analyst with years of experience in
+    gathering market intelligence. You're known for your ability to find
+    relevant and up-to-date market information and present it in a clear,
+    actionable format.""",
+    tools=[SearchTool()],
+    verbose=True
 )
 
 # rest of the code ...
 ```
 
 ## Conclusion
 
-Tools are pivotal in extending the capabilities of CrewAI agents, enabling them to undertake a broad spectrum of tasks and collaborate effectively. 
-When building solutions with CrewAI, leverage both custom and existing tools to empower your agents and enhance the AI ecosystem. Consider utilizing error handling, caching mechanisms, 
-and the flexibility of tool arguments to optimize your agents' performance and capabilities.
+Tools are pivotal in extending the capabilities of CrewAI agents, enabling them to undertake a broad spectrum of tasks and collaborate effectively.
+When building solutions with CrewAI, leverage both custom and existing tools to empower your agents and enhance the AI ecosystem. Consider utilizing error handling, caching mechanisms,
+and the flexibility of tool arguments to optimize your agents' performance and capabilities.