booking_chest — Cal.com MCP Server

A Model Context Protocol server for Cal.com open-source scheduling. Exposes ~70 MCP tools across 10 resource modules — create schedules, manage event types, book meetings, integrate calendars, configure webhooks, and manage teams — all controllable directly from Claude or any MCP-compatible client.

Features

• ~70 tools covering the Cal.com API v2

• Clean two-layer architecture: pure calcom_client/ package + thin MCP wrapper

• Static Bearer token auth (no refresh needed)

• Typed exception hierarchy (APIError, NotFoundError, ValidationError, AuthenticationError)

• API quirks baked in (correct parameter names, required fields, response envelope unwrapping)

Related MCP server: Calendly MCP Server

Resource Modules (10)

Installation

git clone https://github.com/dsddet/booking_chest
cd booking_chest
pip install -e ".[mcp]"

Or with uv (recommended):

uv pip install -e ".[mcp]"

Environment Variables

Create a .env file:

CALCOM_API_KEY=cal_your_api_key_here
CALCOM_BASE_URL=https://api.cal.com

For self-hosted Cal.com instances, set CALCOM_BASE_URL to your instance URL (e.g., http://192.168.0.214).

Getting an API Key

1. Log into Cal.com Settings → Developer → API Keys

2. Click "Generate API Key"

3. Copy the key (starts with cal_) — it cannot be retrieved later

Claude Desktop Configuration

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "booking_chest": {
      "command": "uv",
      "args": [
        "--directory", "/path/to/booking_chest",
        "run", "--extra", "mcp", "mcp_server.py"
      ],
      "env": {
        "CALCOM_API_KEY": "cal_your_api_key_here",
        "CALCOM_BASE_URL": "https://api.cal.com"
      }
    }
  }
}

Replace /path/to/booking_chest with the absolute path to your cloned directory.

Usage Examples

Once connected, you can ask Claude:

• "Create a 30-minute consultation event type"

• "What slots are available this week for event type 1?"

• "Book a meeting with john@example.com on March 5th at 2pm Eastern"

• "List all my upcoming bookings"

• "Cancel booking 42 — attendee has a conflict"

• "Connect my Google Calendar and set it as the destination"

• "Create a webhook to notify Zapier when bookings are created or cancelled"

• "List all team members and their roles"

Architecture

calcom_client/          # Pure API client (no MCP dependency)
├── http.py             # httpx + Bearer token auth + response envelope unwrap
├── exceptions.py       # APIError, NotFoundError, ValidationError, AuthenticationError
├── me.py               # Profile get/update
├── timezones.py        # List all timezones
├── api_keys.py         # API key rotation
├── schedules.py        # Availability schedule CRUD
├── event_types.py      # Event type CRUD + webhooks + private links
├── slots.py            # Available slots, reserve, delete
├── bookings.py         # Booking CRUD (cancel, reschedule, no-show)
├── calendars.py        # Calendar integrations (Google, Office 365, Apple)
├── webhooks.py         # User-level webhook CRUD
├── teams.py            # Team CRUD + memberships + event types + invite
└── __init__.py         # CalcomClient facade composing all modules
mcp_server.py           # ~70 @mcp.tool() functions

Cal.com API Quirks (baked into client code)

• API version: Use cal-api-version: 2024-06-14 (broadest support — 2024-08-13 misses some endpoints)

• Response envelope: All responses wrapped in {"status": "success", "data": ...} — unwrapped automatically

• Slots params: Use start/end (NOT startTime/endTime — those cause 400 errors)

• Webhook triggers: Use triggers field (NOT eventTriggers — old doc error)

• Calendar connect: Use google, office365, apple (NOT google-calendar, office365calendar)

• calendarsToLoad is REQUIRED for busy-times endpoint (400 error without it)

• isDefault is REQUIRED when creating schedules (400 error without it)

• slotId is REQUIRED when reserving slots

• API key refresh: Old key invalidated immediately — update env before next request

• Team creation needs Stripe — use existing teams or configure Stripe billing

• metadata PATCH: Returns null in response but IS saved (verify via team memberships)

• No team-level webhooks — webhooks are always scoped to specific event types

License

MIT