google-cal-mcp

MCP server for Google Calendar - list, create, update, and manage calendar events.

Use Cases

Schedule meetings: "Set up a 30-min sync with Sarah next week" → finds a free slot, creates the event with a Meet link, and sends the invite.

RSVP to invites: "Accept the team offsite but decline the vendor demo" → responds to pending invitations automatically.

Find availability: "When am I free this Thursday afternoon?" → queries your calendar and returns open slots.

Reschedule events: "Move my 1:1 with Alex to Friday at 2pm" → updates the event and notifies attendees.

Daily briefing: "What's on my calendar today?" → lists all events with times, locations, and attendees.

Block focus time: "Block 2 hours tomorrow morning for deep work" → creates a calendar event to protect your time.

(These are just examples - any workflow that needs calendar access can use this.)

Go to Google Cloud Console
Create a new project (or use existing)
Enable the Google Calendar API
Go to APIs & Services → OAuth consent screen, set up consent screen
Go to APIs & Services → Credentials → Create Credentials → OAuth client ID
Choose Web application
Add http://localhost:3000/callback to Authorized redirect URIs
Note your Client ID and Client Secret

GOOGLE_CLIENT_ID='your-client-id' \
GOOGLE_CLIENT_SECRET='your-client-secret' \
MCP_TRANSPORT=http \
npm start

The server runs on http://localhost:3000 by default. Change with PORT=3001.

claude mcp add --transport http google-cal-mcp http://localhost:3000/mcp

This server acts as an OAuth proxy to Google:

graph LR
    A[MCP client] <--> B[google-cal-mcp] <--> C[Google OAuth/API]

Server advertises itself as an OAuth authorization server via /.well-known/oauth-authorization-server
/register returns the Google OAuth client credentials
/authorize redirects to Google, encoding the client's callback URL in state
/callback receives the code from Google and forwards to the client's callback
/token proxies token requests to Google, injecting client credentials
/mcp handles MCP requests, using the bearer token to call Calendar API

The server holds no tokens or state - it just proxies OAuth to Google.

Tool	Description
Calendars
`calendars_list`	List all calendars the user has access to
`calendarlist_insert`	Subscribe to a shared calendar
`calendarlist_update`	Update calendar settings (color, visibility, reminders)
`calendarlist_delete`	Unsubscribe from a calendar
Events
`events_list`	List events in a time range with search/filter
`event_get`	Get details of a specific event
`event_create`	Create a new event with attendees and Meet link
`event_update`	Update an existing event
`event_delete`	Delete an event
`event_respond`	RSVP to an invitation (accept/decline/tentative)
`event_move`	Move event to a different calendar
`event_instances`	Get instances of a recurring event
Availability
`freebusy_query`	Find free/busy times for scheduling
Sharing
`acl_list`	List who has access to a calendar
Colors
`colors_get`	Get available color palette for calendars/events

Pull requests are welcomed on GitHub! To get started:

To release: