MCP macOS Calendar

MCP macOS Calendar is a Rust MCP server that exposes Apple Calendar data through EventKit. It supports stdio for desktop MCP clients and HTTP transport for local browser or Electron clients.

The server can list calendars, read calendar events, and optionally create, update, or delete calendars and events. Use --read-only when a client should only be allowed to inspect calendar data.

Features

• Native macOS Calendar access through EventKit.
• MCP tools for calendars and events.
• Stdio transport for Claude Desktop and similar clients.
• Legacy SSE endpoints at /sse and /message.
• Streamable HTTP endpoint at /mcp.
• Optional read-only mode that hides mutation tools.
• Embedded Info.plist calendar usage description for macOS permission prompts.

Requirements

• macOS with Calendar access available.
• Rust 1.80 or newer.
• Xcode Command Line Tools for coverage reporting with xcrun llvm-profdata and xcrun llvm-cov.

Build

cargo build --release

The release binary is written to:

target/release/mcp-macos-calendar

Run

Run over stdio:

cargo run -- --transport stdio

Run over HTTP on the default host and port:

cargo run -- --transport sse

Run over HTTP on a custom host and port:

cargo run -- --transport sse --host 127.0.0.1 --port 8080

Run in read-only mode:

cargo run -- --transport stdio --read-only

When macOS asks for permission, grant Calendar access in System Settings, Privacy & Security, Calendars.

MCP Endpoints

When started with --transport sse --host 127.0.0.1 --port 8080:

• Legacy SSE: http://127.0.0.1:8080/sse
• Legacy message POST: http://127.0.0.1:8080/message
• Streamable HTTP: http://127.0.0.1:8080/mcp

Claude Desktop

Stdio configuration:

{
  "mcpServers": {
    "macos-calendar": {
      "command": "/absolute/path/to/mcp-macos-calendar",
      "args": ["--transport", "stdio"]
    }
  }
}

Read-only stdio configuration:

{
  "mcpServers": {
    "macos-calendar": {
      "command": "/absolute/path/to/mcp-macos-calendar",
      "args": ["--transport", "stdio", "--read-only"]
    }
  }
}

HTTP/SSE configuration:

{
  "mcpServers": {
    "macos-calendar": {
      "url": "http://127.0.0.1:8080/sse"
    }
  }
}

Use the built binary path from target/release/mcp-macos-calendar, or install/copy the binary to a stable location and point command there.

Tools

| Tool | Mode | Description | | --- | --- | --- | | getCalendars | read | List available macOS calendars. | | getCalendarEvents | read | List events from a calendar with optional date filters and pagination. | | createCalendar | write | Create a new calendar. | | deleteCalendar | write | Delete a calendar. | | createCalendarEvent | write | Create an event in a calendar. | | updateCalendarEvent | write | Update selected event fields. | | deleteCalendarEvent | write | Delete an event. |

In --read-only mode, only getCalendars and getCalendarEvents are exposed.

Tool Parameters

getCalendars takes no parameters.

getCalendarEvents:

{
  "calendar_id": "calendar-id",
  "start_date": "2026-06-01T00:00:00",
  "end_date": "2026-06-30T23:59:59",
  "limit": 100,
  "offset": 0
}

start_date, end_date, limit, and offset are optional. Without dates, the server uses a default window from 30 days before now to 30 days after now. limit defaults to 100 and cannot exceed 1000.

createCalendar:

{
  "title": "Work",
  "color": "#FF0000"
}

deleteCalendar:

{
  "calendar_id": "calendar-id"
}

createCalendarEvent:

{
  "calendar_id": "calendar-id",
  "title": "Planning",
  "start_date": "2026-06-15T10:00:00",
  "end_date": "2026-06-15T11:00:00",
  "location": "Office",
  "notes": "Weekly planning"
}

updateCalendarEvent:

{
  "calendar_id": "calendar-id",
  "event_id": "event-id",
  "title": "Updated planning",
  "start_date": "2026-06-15T10:30:00",
  "end_date": "2026-06-15T11:30:00",
  "location": "Conference room",
  "notes": "Bring notes"
}

deleteCalendarEvent:

{
  "calendar_id": "calendar-id",
  "event_id": "event-id"
}

Test

Run all tests:

cargo test

Run integration tests only:

cargo test --test integration_main

Some service tests touch EventKit. If calendar access is unavailable, those tests print a skip message and return without failing.

Coverage

See COVERAGE.md for the current coverage report and the exact commands used to regenerate it.

just coverage
just coverage --update-coverage-md

Development

Useful just recipes:

just build
just test
just run-stdio
just run-sse
just lint

License

This project is licensed under the MIT License - see the LICENSE file for details.