io.github.AIWerk/mcp-server-cal

@aiwerk/mcp-server-cal

Cal.com scheduling MCP server - manage bookings, event types, and availability directly from your AI assistant.

Why this server?

Connect Claude, Cursor, or any MCP-compatible AI to your Cal.com account. Create bookings, check availability, manage event types, and view schedules - all via natural language.

Install

Two ways to run this server — pick the one that fits.

Option 1 — Hosted (zero setup)

No local runtime, no env vars on your machine — secrets are AES-256-GCM encrypted server-side via HashiCorp Vault.

1. Sign up at aiwerkmcp.com.
2. Install Cal.com from the catalog and paste your CAL_API_KEY.
3. Point your MCP client (Claude.ai, Cursor, Hermes, …) at your hosted endpoint:

   https://bridge.aiwerk.ch/u/<your-user-id>/mcp
   

   with your Bearer token.

All 12 tools, 3 resources, and 3 prompts appear. Install other AIWerk recipes from the same bridge.

Option 2 — Self-hosted (npx)

Run directly — you manage the API key:

CAL_API_KEY=cal_live_your_api_key_here npx @aiwerk/mcp-server-cal

Or wire it into your MCP client config — see Configuration below.

Tools

Tool	Description
cal_list_bookings	List bookings with optional filters (status, event type, date range)
cal_get_booking	Get details of a specific booking by UID
cal_create_booking	Create a new booking (event type, attendee info, time)
cal_cancel_booking	Cancel a booking by UID
cal_reschedule_booking	Reschedule a booking to a new time
cal_list_event_types	List all event types
cal_get_event_type	Get event type details by ID
cal_create_event_type	Create a new event type
cal_update_event_type	Update an existing event type
cal_delete_event_type	Delete an event type
cal_get_availability	Check available slots for an event type in a date range
cal_list_schedules	List all schedules (working hours / availability rules)

Resources

Resources are automatically available in the AI's context — no need to ask for them.

Resource	URI	Description
Upcoming Bookings	cal://bookings/upcoming	Today's and tomorrow's bookings
Event Types	cal://event-types	All configured event types
Schedules	cal://schedules	Working hours and availability rules

Prompts

Ready-made prompt templates for common scheduling tasks.

Prompt	Description
daily-schedule	Summarize today's schedule with bookings and free slots
find-free-slot	Find next available time for a specific event type
reschedule-suggestion	Suggest alternative times for rescheduling a booking

Configuration

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "cal": {
      "command": "npx",
      "args": ["@aiwerk/mcp-server-cal"],
      "env": {
        "CAL_API_KEY": "cal_live_your_api_key_here"
      }
    }
  }
}

Cursor

Add to .cursor/mcp.json in your project or ~/.cursor/mcp.json globally:

{
  "mcpServers": {
    "cal": {
      "command": "npx",
      "args": ["@aiwerk/mcp-server-cal"],
      "env": {
        "CAL_API_KEY": "cal_live_your_api_key_here"
      }
    }
  }
}

OpenClaw / Universal Recipe

{
  "name": "cal",
  "command": "npx",
  "args": ["@aiwerk/mcp-server-cal"],
  "env": {
    "CAL_API_KEY": "${CAL_API_KEY}"
  }
}

Environment Variables

Variable	Required	Default	Description
CAL_API_KEY	Yes (on tool call)	-	Cal.com API key (cal_ or cal_live_ prefix)
CAL_BASE_URL	No	https://api.cal.com/v2	Override the Cal.com API base URL

The server starts and responds to tools/list without CAL_API_KEY. The key is only required when an actual tool is called (lazy credentials pattern).

Getting Your API Key

1. Go to Cal.com Settings
2. Create a new API key
3. Copy the key (starts with cal_live_ for production)

Security

• Never commit your API key to version control
• Use environment variables or a secrets manager
• The server only reads CAL_API_KEY at tool call time, never logs it

About AIWerk MCP

Part of the AIWerk MCP platform — curated, signed MCP recipes served either as npm packages for self-hosting or through our multi-tenant hosted bridge (bridge.aiwerk.ch).

Other AIWerk MCP servers:

• @aiwerk/mcp-server-imap — IMAP/SMTP email, provider-agnostic
• @aiwerk/mcp-server-wise — Wise (TransferWise) Personal API, read-only
• @aiwerk/mcp-server-clawhub — ClawHub skill catalog

Browse the full catalog (20+ recipes including GitHub, Linear, Notion, Stripe, …) at aiwerkmcp.com.

Contributing

Issues and PRs are welcome! Please open an issue first for larger changes.

License

MIT - AIWerk