Google Calendar AutoAuth MCP Server

A Model Context Protocol (MCP) server for Google Calendar integration in Claude Desktop with auto authentication support. This server enables AI assistants to manage Google Calendar through natural language interactions.


Features

- Create calendar events with title, description, location, and attendees
- Update existing calendar events
- Delete calendar events
- Retrieve event details
- List events within a specified time range
- Search for events by keyword
- List all available calendars
- Support for natural language date/time input (e.g., "tomorrow at 2pm", "next monday")
- Full integration with Google Calendar API
- Simple OAuth2 authentication flow with auto browser launch
- Support for both Desktop and Web application credentials
- Global credential storage for convenience

Installation & Authentication

Installing via Smithery

To install Google Calendar Integration Server for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install @falgom4/calendar-mcp --client claude

Installing Manually

1. Create a Google Cloud Project and obtain credentials:

a. Create a Google Cloud Project:
- Go to Google Cloud Console
- Create a new project or select an existing one
- Enable the Google Calendar API for your project

b. Create OAuth 2.0 Credentials:
- Go to "APIs & Services" > "Credentials"
- Click "Create Credentials" > "OAuth client ID"
- Choose either "Desktop app" or "Web application" as application type
- Give it a name and click "Create"
- For Web application, add http://localhost:3000/oauth2callback to the authorized redirect URIs
- Download the JSON file of your client's OAuth keys
- Rename the key file to gcp-oauth.keys.json

2. Run Authentication:

You can authenticate in two ways:

a. Global Authentication (Recommended):

   # First time: Place gcp-oauth.keys.json in your home directory's .calendar-mcp folder

   mkdir -p ~/.calendar-mcp

   mv gcp-oauth.keys.json ~/.calendar-mcp/

# Run authentication from anywhere

   npx @nchufa/calendar auth

   

b. Local Authentication:

   # Place gcp-oauth.keys.json in your current directory

   # The file will be automatically copied to global config

   npx @nchufa/calendar auth

   

The authentication process will:
- Look for gcp-oauth.keys.json in the current directory or ~/.calendar-mcp/
- If found in current directory, copy it to ~/.calendar-mcp/
- Open your default browser for Google authentication
- Save credentials as ~/.calendar-mcp/credentials.json

> Note:
> - After successful authentication, credentials are stored globally in ~/.calendar-mcp/ and can be used from any directory
> - Both Desktop app and Web application credentials are supported
> - For Web application credentials, make sure to add http://localhost:3000/oauth2callback to your authorized redirect URIs

3. Configure in Claude Desktop:

Add the following to your Claude Desktop configuration file:

{
  "mcpServers": {
    "calendar": {
      "command": "npx",
      "args": [
        "@nchufa/calendar"
      ]
    }
  }
}

Available Tools

The server provides the following tools that can be used through Claude Desktop:

1. Create Event (create_event)

Creates a new calendar event.

{
  "summary": "Team Meeting",
  "description": "Weekly team sync to discuss project progress",
  "location": "Conference Room A",
  "start": "2025-04-01T14:00:00",
  "end": "2025-04-01T15:00:00",
  "attendees": ["colleague@example.com", "manager@example.com"],
  "reminders": {
    "useDefault": false,
    "overrides": [
      {
        "method": "email",
        "minutes": 30
      },
      {
        "method": "popup",
        "minutes": 10
      }
    ]
  }
}

Natural language date/time is also supported:

{
  "summary": "Coffee with John",
  "location": "Starbucks Downtown",
  "start": "tomorrow at 2:30pm",
  "end": "tomorrow at 3:30pm"
}

2. Get Event (get_event)

Retrieves details of a specific calendar event.

{
  "eventId": "abc123xyz456",
  "calendarId": "primary"
}

3. Update Event (update_event)

Updates an existing calendar event.

{
  "eventId": "abc123xyz456",
  "summary": "Updated Meeting Title",
  "location": "New Location",
  "start": "2025-04-01T15:00:00",
  "end": "2025-04-01T16:00:00"
}

4. Delete Event (delete_event)

Deletes a calendar event.

{
  "eventId": "abc123xyz456",
  "calendarId": "primary"
}

5. List Events (list_events)

Lists calendar events within a specified time range.

{
  "calendarId": "primary",
  "timeMin": "2025-04-01T00:00:00",
  "timeMax": "2025-04-07T23:59:59",
  "maxResults": 10,
  "orderBy": "startTime"
}

6. Search Events (search_events)

Searches for events matching a query.

{
  "query": "meeting",
  "calendarId": "primary",
  "timeMin": "2025-04-01T00:00:00",
  "maxResults": 5
}

7. List Calendars (list_calendars)

Lists all available calendars.

{}

Natural Language Date/Time Support

The server supports various natural language formats for dates and times:

- Specific dates: "2025-04-01T14:00:00" (ISO format)
- Simple references: "today", "tomorrow", "now"
- Relative times: "2 hours later", "3 days later"
- Day references: "next monday", "next tuesday"
- Combined formats: "tomorrow at 2pm", "monday at 15:30"

This makes it easy to create and update events using natural language instructions.

Security Notes

- OAuth credentials are stored securely in your local environment (~/.calendar-mcp/)
- The server uses offline access to maintain persistent authentication
- Never share or commit your credentials to version control
- Regularly review and revoke unused access in your Google Account settings

Troubleshooting

1. OAuth Keys Not Found
- Make sure gcp-oauth.keys.json is in either your current directory or ~/.calendar-mcp/
- Check file permissions

2. Invalid Credentials Format
- Ensure your OAuth keys file contains either web or installed credentials
- For web applications, verify the redirect URI is correctly configured

3. Port Already in Use
- If port 3000 is already in use, please free it up before running authentication
- You can find and stop the process using that port

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT

Acknowledgments

Special thanks to GongRzhe and his Calendar-Autoauth-MCP-Server project which served as a foundation for this implementation.

Support

If you encounter any issues or have questions, please file an issue on the GitHub repository.