Cal.com FastMCP Server

You run a FastMCP server that exposes Cal.com capabilities to language learning models and other MCP clients. It lets you query event types, bookings, schedules, teams, users, and webhooks from Cal.com through a lightweight, configurable endpoint you run locally or in your environment.

How to use

Start the MCP server and connect your MCP client to the local endpoint it exposes. The server runs a FastMCP instance that listens for tool calls and forwards them to Cal.com using your API key. Ensure your CALCOM_API_KEY environment variable is set to authenticate requests.

Once the server is running, your MCP client can invoke the available tools to interact with Cal.com data. You can retrieve a list of event types, fetch bookings with optional filters, create bookings for attendees, list schedules and teams, and manage users and webhooks. Each tool returns either the API response or a structured error when something goes wrong.

How to install

Prerequisites you need before starting:

Python 3.8+

A Cal.com account and API Key (v2)

Then install and run the MCP server with the following steps.

# 1. Install Python dependencies (in a virtual environment recommended)
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

# 2. Install required Python packages
pip install -r requirements.txt

# 3. Set your Cal.com API key (environment variable)
export CALCOM_API_KEY="your_actual_api_key_here"  # Linux/macOS
# or on Windows PowerShell
# $env:CALCOM_API_KEY="your_actual_api_key_here"

Running the server

Run the MCP server with the final start command shown here. This starts the server on port 8010 using SSE transport.

fastmcp run app.py --transport sse --port 8010

Security and environment considerations

Never hardcode your CALCOM_API_KEY. Always use environment variables and keep keys out of source control. If you need to rotate keys, update the environment variable and restart the server.

Notes on available tools

The server exposes a set of tools that let you interact with Cal.com programmatically. Each tool returns the API data or a structured error when something goes wrong. Ensure the CALCOM_API_KEY is set before making tool calls.

Available tools

get_api_status

Check if the Cal.com API key is configured in the environment and return a status string.

list_event_types

Fetch a list of all event types from Cal.com for the authenticated account and return the event types or an error message.

get_bookings

Fetch a list of bookings from Cal.com with optional filters (event_type_id, user_id, status, date_from, date_to, limit) and return the bookings or an error message.

create_booking

Create a new booking for a specific event type and attendee with required details like start_time and attendee information, and return the booking details or an error message.

list_schedules

List all schedules available to the authenticated user or a specific user/team with optional filters (user_id, team_id, limit).

list_teams

List all teams available to the authenticated user with an optional limit.

list_users

List all users available to the authenticated account with an optional limit.

list_webhooks

List all webhooks configured for the authenticated account with an optional limit.