How to integrate Outlook MCP with LangChain

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Introduction

This guide walks you through connecting Outlook to LangChain using the Composio tool router. By the end, you'll have a working Outlook agent that can download latest attachments from my inbox, create new calendar for project deadlines, add rule to move newsletters to folder, get my current automatic reply settings through natural language commands.

This guide will help you understand how to give your LangChain agent real control over a Outlook account through Composio's Outlook 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 Outlook project to Composio
  • Create a Tool Router MCP session for Outlook
  • Initialize an MCP client and retrieve Outlook tools
  • Build a LangChain agent that can interact with Outlook
  • 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 Outlook MCP server, and what's possible with it?

The Outlook MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Outlook account. It provides structured and secure access to your email, calendar, and contacts, so your agent can perform actions like sending emails, organizing folders, managing your calendar, and handling attachments on your behalf.

  • Email organization and folder management: Let your agent create, delete, or organize mail folders to keep your inbox tidy and efficient.
  • Calendar and event creation: Easily have your agent set up new calendars, so you can organize meetings and events without lifting a finger.
  • Smart attachments handling: Automatically download files from your emails or add attachments to outgoing messages for seamless file management.
  • Automated rules and filtering: Direct your agent to create email rules that filter, sort, or take action on messages as they arrive.
  • Contact and category organization: Ask your agent to create new contact folders or master categories to streamline how you manage people and projects.

Supported Tools & Triggers

Tools
Triggers
Add mail attachmentTool to add an attachment to an email message.
Create calendarTool to create a new calendar in the signed-in user's mailbox.
Create contact folderTool to create a new contact folder in the user's mailbox.
Create Email RuleCreate email rule filter with conditions and actions
Create mail folderTool to create a new mail folder.
Create master categoryTool to create a new category in the user's master category list.
Delete mail folderDelete a mail folder from the user's mailbox.
Download Outlook attachmentDownloads a specific file attachment from an email message in a microsoft outlook mailbox; the attachment must contain 'contentbytes' (binary data) and not be a link or embedded item.
Get mailbox settingsTool to retrieve mailbox settings.
Get mail deltaTool to retrieve incremental changes (delta) of messages in a mailbox.
Get mail tipsTool to retrieve mail tips such as automatic replies and mailbox full status.
Get master categoriesTool to retrieve the user's master category list.
Get supported languagesTool to retrieve supported languages in the user's mailbox.
Get supported time zonesTool to retrieve supported time zones in the user's mailbox.
List Outlook calendarsTool to list calendars in the signed-in user's mailbox.
List event attachmentsTool to list attachments for a specific outlook calendar event.
List Outlook attachmentsLists metadata (like name, size, and type, but not `contentbytes`) for all attachments of a specified outlook email message.
List event remindersTool to retrieve reminders for events occurring within a specified time range.
Add event attachmentAdds an attachment to a specific outlook calendar event.
Create Calendar EventCreates a new outlook calendar event, ensuring `start datetime` is chronologically before `end datetime`.
Create contactCreates a new contact in a microsoft outlook user's contacts folder.
Create email draftCreates an outlook email draft with subject, body, recipients, and an optional attachment.
Create a draft replyCreates a draft reply in the specified user's outlook mailbox to an existing message (identified by a valid `message id`), optionally including a `comment` and cc/bcc recipients.
Delete ContactPermanently deletes an existing contact, using its `contact id` (obtainable via 'list user contacts' or 'get contact'), from the outlook contacts of the user specified by `user id`.
Delete Calendar EventDeletes an existing calendar event, identified by its unique `event id`, from a specified user's microsoft outlook calendar, with an option to send cancellation notifications to attendees.
Get contactRetrieves a specific outlook contact by its `contact id` from the contacts of a specified `user id` (defaults to 'me' for the authenticated user).
Get contact foldersTool to retrieve a list of contact folders in the signed-in user's mailbox.
Get calendar eventRetrieves the full details of a specific calendar event by its id from a user's outlook calendar, provided the event exists.
Get email messageRetrieves a specific email message by its id from the specified user's outlook mailbox.
Get Outlook profileRetrieves the microsoft outlook profile for a specified user.
Get scheduleRetrieves free/busy schedule information for specified email addresses within a defined time window.
List Outlook contactsRetrieves a user's microsoft outlook contacts, from the default or a specified contact folder.
List eventsRetrieves events from a user's outlook calendar via microsoft graph api, supporting pagination, filtering, property selection, sorting, and timezone specification.
List mail foldersTool to list a user's top-level mail folders.
List MessagesRetrieves a list of email messages from a specified mail folder in an outlook mailbox, with options for filtering (including by conversationid to get all messages in a thread), pagination, and sorting; ensure 'user id' and 'folder' are valid, and all date/time strings are in iso 8601 format.
Move message to folderMove a message to another folder within the specified user's mailbox.
Reply to EmailSends a plain text reply to an outlook email message, identified by `message id`, allowing optional cc and bcc recipients.
Search Outlook messagesSearches messages in a microsoft 365 or enterprise outlook account mailbox, supporting filters for sender, subject, attachments, pagination, and sorting by relevance or date.
Send emailSends an email with subject, body, recipients, and an optional attachment via microsoft graph api; attachments require a non-empty file with valid name and mimetype.
Update calendar eventUpdates specified fields of an existing outlook calendar event.
Update ContactUpdates an existing outlook contact, identified by `contact id` for the specified `user id`, requiring at least one other field to be modified.
Update email messageUpdates specified properties of an existing email message; `message id` must identify a valid message within the specified `user id`'s mailbox.
Update mailbox settingsTool to update mailbox settings for the signed-in user.

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 Outlook 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 Outlook tools
  • Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

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

url = session.mcp.url
What's happening:
  • We're creating a Tool Router session that gives your agent access to Outlook 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 Outlook tools as needed

Configure the agent with the MCP URL

client = MultiServerMCPClient({
    "outlook-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 Outlook MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • get_tools() retrieves all available Outlook 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 Outlook 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 Outlook 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=['outlook']
    )

    url = session.mcp.url
    
    client = MultiServerMCPClient({
        "outlook-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 Outlook 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 Outlook 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 Outlook MCP Agent with another framework

OpenAI Agents SDK

OpenAI Agents SDK

Use Outlook MCP with OpenAI Agents SDK

Claude Agent SDK

Claude Agent SDK

Use Outlook MCP with Claude Agent SDK

Google ADK

Google ADK

Use Outlook MCP with Google ADK

Vercel AI SDK

Vercel AI SDK

Use Outlook MCP with Vercel AI SDK

Mastra AI

Mastra AI

Use Outlook MCP with Mastra AI

LlamaIndex

LlamaIndex

Use Outlook MCP with LlamaIndex

CrewAI

CrewAI

Use Outlook MCP with CrewAI

FAQ

What are the differences in Tool Router MCP and Outlook MCP?

With a standalone Outlook MCP server, the agents and LLMs can only access a fixed set of Outlook tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Outlook 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 Outlook tools.

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

Yes, absolutely. You can configure which Outlook 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 Outlook data and credentials are handled as safely as possible.

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