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Cal MCP Server

Cal.com scheduling management for LLMs via API-based booking and event type automation.

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Overview

This server provides a bridge for LLMs to interface with Cal.com, enabling automated interaction with calendar events and booking workflows. By configuring the server with a Cal.com API key, users can execute commands to create, cancel, or reschedule bookings and manage event types directly through natural language. The project supports a modular approach to tool exposure, allowing users to toggle between core functionality or unlock the full suite of Cal.com API endpoints using the --all-tools configuration flag.

Our verdict

The Cal MCP Server carries a high-risk profile, reflected in its 10/100 security score. The project is community-maintained and has not received an editorial review, and it suffers from a lack of clear legal usage terms due to the absence of a software license. Potential users should note the high bus-factor risk associated with a single-contributor project that has not seen a commit in over 470 days; it is currently only recommended for experimental personal workflows where API key security can be manually managed.

Supports all Cal.com API endpoints via flag
Small attack surface with only two direct dependencies
Includes documented README with setup instructions

Security score of 10/100 indicates significant maintenance risks
Stagnant development with no commits for 476 days
No open source license defined for the repository

Setup

Claude Desktop

{
  "mcpServers": {
    "cal-mcp": {
      "args": [
        "-y",
        "@calcom/cal-mcp"
      ],
      "command": "npx"
    }
  }
}

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows), then restart Claude Desktop. Some servers require API keys or tokens as environment variables — check the project's README and add an "env" object if needed.

No read-only mode — running this grants full read/write access.
No built-in authentication — anyone with access to this config can invoke every tool it exposes.

Tools

Tool	Description	Risk
getBooking	Retrieve information about a specific booking.	low
getBookings	Retrieve a list of bookings.	low
createBooking	Create a new booking.	medium
rescheduleBooking	Reschedule an existing booking.	medium
cancelBooking	Cancel an existing booking.	medium
getEventTypes	Retrieve a list of event types.	low
getEventTypeById	Retrieve information about a specific event type by its ID.	low
updateEventType	Update an existing event type.	medium
deleteEventType	Delete an existing event type.	high

Compatibility

Client	Local	Docker	Remote	Read-only
Claude Desktop
Cursor
VS Code
Windsurf
ChatGPT

Frequently asked questions

›What are the system requirements for running the Cal MCP server?

You need Node.js version 18.0.0 or higher and a compatible MCP client such as Claude Desktop, Cursor, or Windsurf.

›How do I provide my Cal.com API key to the server?

You must include your API key in the environment variables section of your MCP configuration file using the key CAL_API_KEY.

›Which tools are available by default?

The server comes with core tools for managing bookings and event types, including functions like getBookings, createBooking, and deleteEventType.

›Can I access Cal.com endpoints that are not in the default tool list?

Yes, you can enable access to all Cal.com API endpoints by adding the --all-tools or -a flag to the arguments in your MCP configuration.

›Are there any specific security precautions for using this server?

You should never share or commit your Cal.com API key, and you should rotate it immediately in your Cal.com account if it is ever exposed.

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