How to integrate Openweather api MCP with LangChain

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Introduction

This guide walks you through connecting Openweather api to LangChain using the Composio tool router. By the end, you'll have a working Openweather api agent that can get current weather in paris right now, show 5-day forecast for san francisco, check today's air quality in new delhi, find uv index for miami this afternoon through natural language commands.

This guide will help you understand how to give your LangChain agent real control over a Openweather api account through Composio's Openweather api MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

TL;DR

Here's what you'll learn:
  • Get and set up your OpenAI and Composio API keys
  • Connect your Openweather api project to Composio
  • Create a Tool Router MCP session for Openweather api
  • Initialize an MCP client and retrieve Openweather api tools
  • Build a LangChain agent that can interact with Openweather api
  • Set up an interactive chat interface for testing

What is LangChain?

LangChain is a framework for developing applications powered by language models. It provides tools and abstractions for building agents that can reason, use tools, and maintain conversation context.

Key features include:

  • Agent Framework: Build agents that can use tools and make decisions
  • MCP Integration: Connect to external services through Model Context Protocol adapters
  • Memory Management: Maintain conversation history across interactions
  • Multi-Provider Support: Works with OpenAI, Anthropic, and other LLM providers

What is the Openweather api MCP server, and what's possible with it?

The Openweather api MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Openweather api account. It provides structured and secure access to real-time, forecasted, and historical weather data, so your agent can fetch current conditions, deliver forecasts, analyze air quality, and perform location-based weather insights on your behalf.

  • Current weather retrieval: Instantly get up-to-the-minute weather details for any city or geographic coordinate, including temperature, humidity, and wind.
  • Five-day weather forecasting: Ask your agent for detailed 5-day forecasts in 3-hour intervals to plan events, travel, or outdoor activities.
  • Air pollution and UV index analysis: Retrieve current, forecasted, and historical air pollution data, as well as UV index values, to monitor environmental quality for any location.
  • Geocoding and reverse geocoding: Convert location names to coordinates or find city/state information from latitude and longitude, enabling location-aware weather queries.
  • Radius-based weather search: Fetch weather conditions for all cities within a specified radius around a geographic point for broader regional analysis.

Supported Tools & Triggers

Tools
Delete Weather StationTool to delete a registered weather station.
Get 5 Day ForecastTool to get a 5-day forecast every 3 hours.
Get Current Air Pollution DataTool to fetch current air pollution data for a location.
Get Air Pollution ForecastTool to get forecasted air pollution data for a specific location.
Get Air Pollution HistoryTool to retrieve historical air pollution data.
Get Circle City WeatherTool to search for current weather data in cities around a geographic point.
Get Current WeatherTool to retrieve current weather data for a location.
Get Direct GeocodingTool to convert a location name into geographic coordinates.
Get Reverse GeocodingTool to convert geographic coordinates into a location name.
Get Current UV IndexTool to retrieve current uv index for a location.
Get UV Index ForecastTool to retrieve uv index forecast for a specific location.
Get UV Index HistoryTool to retrieve historical uv index data for a specified location and time range.
Get Weather Map Tile (2.0)Tool to fetch weather maps 2.
Get Weather StationsTool to list all weather stations added to your account.
Get Weather TriggersTool to retrieve weather triggers for specific conditions.
Add Weather StationTool to add a new weather station to your account.
Update Weather StationTool to update weather station details.

What is the Composio tool router, and how does it fit here?

What is Tool Router?

Composio's Tool Router helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Tool Router

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Tool Router works

The Tool Router follows a three-phase workflow:

  1. Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
  2. Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
  3. Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Prerequisites

Before starting this tutorial, make sure you have:
  • Python 3.10 or higher installed on your system
  • A Composio account with an API key
  • An OpenAI API key
  • Basic familiarity with Python and async programming

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key. You'll need credits to use the models, or you can connect to another model provider.
  • Keep the API key safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Navigate to your API settings and generate a new API key.
  • Store this key securely as you'll need it for authentication.

Install dependencies

pip install composio-langchain langchain-mcp-adapters langchain python-dotenv

Install the required packages for LangChain with MCP support.

What's happening:

  • composio-langchain provides Composio integration for LangChain
  • langchain-mcp-adapters enables MCP client connections
  • langchain is the core agent framework
  • python-dotenv loads environment variables

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_composio_user_id_here
OPENAI_API_KEY=your_openai_api_key_here

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your requests to Composio's API
  • COMPOSIO_USER_ID identifies the user for session management
  • OPENAI_API_KEY enables access to OpenAI's language models

Import dependencies

from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import create_agent
from dotenv import load_dotenv
from composio import Composio
import asyncio
import os

load_dotenv()
What's happening:
  • We're importing LangChain's MCP adapter and Composio SDK
  • The dotenv import loads environment variables from your .env file
  • This setup prepares the foundation for connecting LangChain with Openweather api functionality through MCP

Initialize Composio client

async def main():
    composio = Composio(api_key=os.getenv("COMPOSIO_API_KEY"))

    if not os.getenv("COMPOSIO_API_KEY"):
        raise ValueError("COMPOSIO_API_KEY is not set")
    if not os.getenv("COMPOSIO_USER_ID"):
        raise ValueError("COMPOSIO_USER_ID is not set")
What's happening:
  • We're loading the COMPOSIO_API_KEY from environment variables and validating it exists
  • Creating a Composio instance that will manage our connection to Openweather api tools
  • Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

# Create Tool Router session for Openweather api
session = composio.create(
    user_id=os.getenv("COMPOSIO_USER_ID"),
    toolkits=['openweather_api']
)

url = session.mcp.url
What's happening:
  • We're creating a Tool Router session that gives your agent access to Openweather api tools
  • The create method takes the user ID and specifies which toolkits should be available
  • The returned session.mcp.url is the MCP server URL that your agent will use
  • This approach allows the agent to dynamically load and use Openweather api tools as needed

Configure the agent with the MCP URL

client = MultiServerMCPClient({
    "openweather_api-agent": {
        "transport": "streamable_http",
        "url": session.mcp.url,
        "headers": {
            "x-api-key": os.getenv("COMPOSIO_API_KEY")
        }
    }
})

tools = await client.get_tools()

agent = create_agent("gpt-5", tools)
What's happening:
  • We're creating a MultiServerMCPClient that connects to our Openweather api MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • get_tools() retrieves all available Openweather api tools that the agent can use
  • We're creating a LangChain agent using the GPT-5 model

Set up interactive chat interface

conversation_history = []

print("Chat started! Type 'exit' or 'quit' to end the conversation.\n")
print("Ask any Openweather api related question or task to the agent.\n")

while True:
    user_input = input("You: ").strip()

    if user_input.lower() in ['exit', 'quit', 'bye']:
        print("\nGoodbye!")
        break

    if not user_input:
        continue

    conversation_history.append({"role": "user", "content": user_input})
    print("\nAgent is thinking...\n")

    response = await agent.ainvoke({"messages": conversation_history})
    conversation_history = response['messages']
    final_response = response['messages'][-1].content
    print(f"Agent: {final_response}\n")
What's happening:
  • We initialize an empty conversation_history list to maintain context across interactions
  • A while loop continuously accepts user input from the command line
  • When a user types a message, it's added to the conversation history and sent to the agent
  • The agent processes the request using the ainvoke() method with the full conversation history
  • Users can type 'exit', 'quit', or 'bye' to end the chat session gracefully

Run the application

if __name__ == "__main__":
    asyncio.run(main())
What's happening:
  • We call the main() function using asyncio.run() to start the application

Complete Code

Here's the complete code to get you started with Openweather api and LangChain:

from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import create_agent
from dotenv import load_dotenv
from composio import Composio
import asyncio
import os

load_dotenv()

async def main():
    composio = Composio(api_key=os.getenv("COMPOSIO_API_KEY"))
    
    if not os.getenv("COMPOSIO_API_KEY"):
        raise ValueError("COMPOSIO_API_KEY is not set")
    if not os.getenv("COMPOSIO_USER_ID"):
        raise ValueError("COMPOSIO_USER_ID is not set")
    
    session = composio.create(
        user_id=os.getenv("COMPOSIO_USER_ID"),
        toolkits=['openweather_api']
    )

    url = session.mcp.url
    
    client = MultiServerMCPClient({
        "openweather_api-agent": {
            "transport": "streamable_http",
            "url": url,
            "headers": {
                "x-api-key": os.getenv("COMPOSIO_API_KEY")
            }
        }
    })
    
    tools = await client.get_tools()
  
    agent = create_agent("gpt-5", tools)
    
    conversation_history = []
    
    print("Chat started! Type 'exit' or 'quit' to end the conversation.\n")
    print("Ask any Openweather api related question or task to the agent.\n")
    
    while True:
        user_input = input("You: ").strip()
        
        if user_input.lower() in ['exit', 'quit', 'bye']:
            print("\nGoodbye!")
            break
        
        if not user_input:
            continue
        
        conversation_history.append({"role": "user", "content": user_input})
        print("\nAgent is thinking...\n")
        
        response = await agent.ainvoke({"messages": conversation_history})
        conversation_history = response['messages']
        final_response = response['messages'][-1].content
        print(f"Agent: {final_response}\n")

if __name__ == "__main__":
    asyncio.run(main())

Conclusion

You've successfully built a LangChain agent that can interact with Openweather api through Composio's Tool Router.

Key features of this implementation:

  • Dynamic tool loading through Composio's Tool Router
  • Conversation history maintenance for context-aware responses
  • Async Python provides clean, efficient execution of agent workflows
You can extend this further by adding error handling, implementing specific business logic, or integrating additional Composio toolkits to create multi-app workflows.

How to build Openweather api MCP Agent with another framework

OpenAI Agents SDK

OpenAI Agents SDK

Use Openweather api MCP with OpenAI Agents SDK

Claude Agent SDK

Claude Agent SDK

Use Openweather api MCP with Claude Agent SDK

Google ADK

Google ADK

Use Openweather api MCP with Google ADK

Vercel AI SDK

Vercel AI SDK

Use Openweather api MCP with Vercel AI SDK

Mastra AI

Mastra AI

Use Openweather api MCP with Mastra AI

LlamaIndex

LlamaIndex

Use Openweather api MCP with LlamaIndex

CrewAI

CrewAI

Use Openweather api MCP with CrewAI

FAQ

What are the differences in Tool Router MCP and Openweather api MCP?

With a standalone Openweather api MCP server, the agents and LLMs can only access a fixed set of Openweather api tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Openweather api and many other apps based on the task at hand, all through a single MCP endpoint.

Can I use Tool Router MCP with LangChain?

Yes, you can. LangChain fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Openweather api tools.

Can I manage the permissions and scopes for Openweather api while using Tool Router?

Yes, absolutely. You can configure which Openweather api scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

How safe is my data with Composio Tool Router?

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Openweather api data and credentials are handled as safely as possible.

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