How do I resolve the 'bind_tools' AttributeError when creating a React Agent with LangGraph?

The error

  AttributeError: 'OpenAI' object has no attribute 'bind_tools'

occurs because the OpenAI model class you are using (from langchain_openai) does not include the method .bind_tools. Under the hood, create_react_agent expects that the model you pass in has a .bind_tools method so it can properly bind the provided tools to the model.

In the LangGraph and LangChain ecosystem, the updated approach is to use a chat model class (for example, ChatOpenAI from langchain.chat_models) that implements such methods. The documentation and examples show that create_react_agent should be initialized with a model that supports tool binding.

To fix the issue, update your model initialization to use ChatOpenAI. For instance:

PYTHONCopied
import os
from dotenv import load_dotenv
from langchain.chat_models import ChatOpenAI  # Import ChatOpenAI instead
from langchain_community.utilities import GoogleSerperAPIWrapper
from langgraph.prebuilt import create_react_agent
from langchain.agents import Tool  # Ensure you're using the proper Tool class

load_dotenv()
openai_api_key = os.getenv("OPENAI_API_KEY")
serper_api_key = os.getenv("SERPER_API_KEY")

# Use ChatOpenAI which supports bind_tools
llm = ChatOpenAI(temperature=0, openai_api_key=openai_api_key, model="gpt-4")

search = GoogleSerperAPIWrapper()

tools = [
    Tool(
        name="Intermediate Answer",
        func=search.run,
        description="useful for when you need to ask with search",
    )
]

agent_executor = create_react_agent(llm, tools=tools)

inputs = {"messages": [("user", "what is the hometown of the reigning men's U.S. Open champion?")]}
response = agent_executor.stream(inputs, stream_mode="values")

Key Points:

• Switch to ChatOpenAI: Use a model class that supports .bind_tools (such as ChatOpenAI) instead of the base OpenAI model.
• Tool Binding: create_react_agent automatically calls .bind_tools on the provided model.
• Deprecation Warnings: The deprecation warning about importing from langchain.agents (e.g., AgentType, Tool, initialize_agent) suggests moving to the recommended updated functions and classes shown in the current documentation.

By using ChatOpenAI, your model will have the required .bind_tools method, and the create_react_agent function should work as expected.