How to integrate Calendly MCP with LangChain

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Introduction

This guide walks you through connecting Calendly to LangChain using the Composio tool router. By the end, you'll have a working Calendly agent that can create a single-use scheduling link for my next meeting, cancel my 2pm event with a reason, mark an invitee as no-show for today's appointment, delete all invitee data for privacy compliance through natural language commands.

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

The Calendly MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Calendly account. It provides structured and secure access to your scheduling workflows, so your agent can perform actions like creating personalized scheduling links, managing events, handling invitee statuses, and automating reminders on your behalf.

  • Instant scheduling link creation: Direct your agent to generate single-use or shareable scheduling links so others can book time with you instantly—no more back-and-forth emails.
  • Automated event and invitee management: Have your agent cancel events, mark invitees as no-shows, or remove no-show statuses to keep your calendar accurate and up to date.
  • Custom one-off event setup: Empower your agent to create unique, one-off meeting types for special situations, bypassing your regular availability rules.
  • Webhook subscription automation: Let the agent set up webhook subscriptions to trigger notifications or workflows in real time when events happen in your Calendly account.
  • Data privacy and compliance actions: Instruct your agent to delete invitee data or scheduled event records as needed for privacy or regulatory compliance, especially for enterprise use cases.

Supported Tools & Triggers

Tools
Cancel eventPermanently cancels an existing, active scheduled event by its `uuid`, optionally providing a `reason`, which may trigger notifications to invitees.
Create an invitee no-showMarks an invitee, identified by their existing and valid uri, as a 'no show' for a scheduled event.
Create One-Off Event TypeCreates a temporary calendly one-off event type for unique meetings outside regular availability, requiring valid host/co-host uris, a future date/range for `date setting`, and a positive `duration`.
Create scheduling linkCreate a single-use scheduling link.
Create shareCreates a customizable, one-time share link for a calendly event type, allowing specific overrides to its settings (e.
Create single use scheduling linkCreates a one-time, single-use scheduling link for an active calendly event type, expiring after one booking.
Create webhook subscriptionCreates a calendly webhook subscription to notify a specified `url` (which must be a publicly accessible https endpoint) for selected `events` within a given `organization` and `scope`.
Delete invitee dataPermanently removes all invitee data associated with the provided emails from past organization events, for data privacy compliance (requires enterprise subscription; deletion may take up to one week).
Delete invitee no showDeletes an invitee no-show record by its `uuid` to reverse an invitee's 'no-show' status; the `uuid` must refer to an existing record.
Delete scheduled event dataFor enterprise users, initiates deletion of an organization's scheduled event data between a `start time` and `end time` (inclusive, where `start time` must be <= `end time`); actual data deletion may take up to 7 days to complete.
Delete webhook subscriptionDeletes an existing webhook subscription to stop calendly sending event notifications to its registered callback url; this operation is idempotent.
Get current userRetrieves detailed information about the currently authenticated calendly user.
Get eventUse to retrieve a specific calendly scheduled event by its uuid, provided the event exists in the user's calendly account.
Get event inviteeRetrieves detailed information about a specific invitee of a scheduled event, using their unique uuids.
Get event typeRetrieves details for a specific calendly event type, identified by its uuid, which must be valid and correspond to an existing event type.
Get groupRetrieves all attributes of a specific calendly group by its uuid; the group must exist.
Get group relationshipRetrieves a specific calendly group relationship by its valid and existing uuid, providing details on user-group associations and membership.
Get invitee no showRetrieves details for a specific invitee no show record by its uuid; an invitee no show is marked when an invitee does not attend a scheduled event.
Get organization invitationRetrieves a specific calendly organization invitation using its uuid and the parent organization's uuid.
Get organization membershipRetrieves a specific calendly organization membership by its uuid, returning all its attributes.
Get routing formRetrieves a specific routing form by its uuid, providing its configuration details including questions and routing logic.
Get userRetrieves comprehensive details for an existing calendly user.
Get user availability scheduleRetrieves an existing user availability schedule by its uuid; this schedule defines the user's default hours of availability.
Get webhook subscriptionRetrieves the details of an existing webhook subscription, identified by its uuid, including its callback url, subscribed events, scope, and state.
Invite user to organizationInvites a user to the specified calendly organization by email, if they aren't already a member and lack a pending invitation to it.
List activity log entriesRetrieves a list of activity log entries for a specified calendly organization (requires an active enterprise subscription), supporting filtering, sorting, and pagination.
List event inviteesRetrieves a list of invitees for a specified calendly event uuid, with options to filter by status or email, and sort by creation time.
List eventsRetrieves a list of scheduled calendly events; requires `user`, `organization`, `group`, or `invitee email` for scope, and admin rights may be needed when filtering by `organization` or `group`.
List event type available timesFetches available time slots for a calendly event type within a specified time range; results are not paginated.
List event type hostsRetrieves a list of hosts (users) assigned to a specific, existing calendly event type, identified by its uri.
List group relationshipsRetrieves a list of group relationships defining an owner's role (e.
List groupsReturns a list of groups for a specified calendly organization uri, supporting pagination.
List organization invitationsRetrieves a list of invitations for a specific organization, identified by its uuid.
List organization membershipsRetrieves a list of organization memberships.
List outgoing communicationsRetrieves a list of outgoing sms communications for a specified organization; requires an enterprise subscription and if filtering by creation date, both `min created at` and `max created at` must be provided to form a valid range.
List routing formsRetrieves routing forms for a specified organization; routing forms are questionnaires used to direct invitees to appropriate booking pages or external urls.
List user availability schedulesRetrieves all availability schedules for the specified calendly user.
List user busy timesFetches a user's busy time intervals (internal and external calendar events) in ascending order for a period up to 7 days; keyset pagination is not supported.
List user event typesRetrieves event types for a user or organization; requires either the `user` or `organization` uri.
List webhook subscriptionsRetrieves webhook subscriptions for a calendly organization; `scope` determines if `user` or `group` uri is also required for filtering.
Remove user from organizationRemoves a user (who is not an owner) from an organization by their membership uuid, requiring administrative privileges.
Revoke a user's organization invitationRevokes a pending and revokable (not yet accepted or expired) organization invitation using its uuid and the organization's uuid, rendering the invitation link invalid.

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

Create a Tool Router session

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

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

Configure the agent with the MCP URL

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

    url = session.mcp.url
    
    client = MultiServerMCPClient({
        "calendly-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 Calendly 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 Calendly 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.

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FAQ

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

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

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

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

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