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 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

• Run Authentication:

You can authenticate in two ways:

a. Global Authentication (Recommended):

```shell
# 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:

shell # 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

1. Configure in Claude Desktop:

Add the following to your Claude Desktop configuration file:

json { "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": ["[email protected]", "[email protected]"],
  "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
2. Make sure gcp-oauth.keys.json is in either your current directory or ~/.calendar-mcp/
3. Check file permissions
4. Invalid Credentials Format
5. Ensure your OAuth keys file contains either web or installed credentials
6. For web applications, verify the redirect URI is correctly configured
7. Port Already in Use
8. If port 3000 is already in use, please free it up before running authentication
9. 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.

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Google Calendar MCP server with auto authentication support

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