How do I install Cal?

Cal is a local plugin. Install it using npm package: @aiwerk/mcp-server-cal and add the generated configuration snippet to your AI app's MCP config file. Then restart your AI app.

What credentials does Cal need?

Cal requires the following credentials or environment variables: CAL_API_KEY. You can find setup instructions on the server detail page.

What AI apps work with Cal?

Cal uses the Model Context Protocol (MCP) and works with any MCP-compatible AI app, including Claude, ChatGPT / Codex, Gemini, Copilot, Cursor, and more.

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Cal MCP Server

by AIWerk

Developer ToolsModerate5.2MCP RegistryLocal

Free

Server data from the Official MCP Registry

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

5.2

Moderate5.2Moderate Risk

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.

env_vars

Check that this permission is expected for this type of plugin.

HTTP Network Access

Connects to external APIs or services over the internet.

What You'll Need

Set these up before or after installing:

Cal.com API key (prefix cal_ or cal_live_). Create one at Cal.com Settings > Security > API Keys.Required

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 GitHub

From 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:
```
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

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_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

Reviews

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Cal MCP Server

About

Security Report

Findings (9)Action required

Permissions Required

What You'll Need

How to Install

Documentation

@aiwerk/mcp-server-cal

Why this server?

Install

Option 1 — Hosted (zero setup)

Option 2 — Self-hosted (npx)

Tools

Resources

Prompts

Configuration

Claude Desktop

Cursor

OpenClaw / Universal Recipe

Environment Variables

Getting Your API Key

Security

About AIWerk MCP

Contributing

License

Reviews

No reviews yet

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