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Cal.com scheduling MCP server: manage bookings, event types, and availability.
About
Cal.com scheduling MCP server: manage bookings, event types, and availability.
Security Report
This is a well-structured Cal.com MCP server with proper authentication, secure credential handling, and good input validation. The server uses lazy credential loading (credentials only required at tool call time, not at startup), stores the API key in environment variables only, and implements proper URL encoding for path parameters. Minor code quality observations around broad error catching and logging practices do not significantly impact the security posture. Supply chain analysis found 4 known vulnerabilities in dependencies (1 critical, 3 high severity). Package verification found 1 issue.
7 files analyzed · 9 issues found
Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.
Permissions Required
This plugin requests these system permissions. Most are normal for its category.
What You'll Need
Set these up before or after installing:
Environment variable: CAL_API_KEY
How to Install
Add this to your MCP configuration file:
{
"mcpServers": {
"io-github-aiwerk-mcp-server-cal": {
"env": {
"CAL_API_KEY": "your-cal-api-key-here"
},
"args": [
"-y",
"@aiwerk/mcp-server-cal"
],
"command": "npx"
}
}
}Documentation
View on GitHubFrom the project's GitHub README.
@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.
- Sign up at aiwerkmcp.com.
- Install Cal.com from the catalog and paste your
CAL_API_KEY. - Point your MCP client (Claude.ai, Cursor, Hermes, …) at your hosted endpoint:
with your Bearer token.https://bridge.aiwerk.ch/u/<your-user-id>/mcp
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
- Go to Cal.com Settings
- Create a new API key
- 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_KEYat 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
Reviews
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