Connect Microsoft 365 calendars to Claude and ChatGPT
Multi Calendar connects work and school calendars on Microsoft 365 to Claude and ChatGPT with Microsoft sign-in, once your organisation allows it.
For calendars Microsoft hosts in Exchange Online - not your organisation's own Exchange server.
The AI apps' own connectors
- Microsoft 365, Anthropic's connector in Claude's directory, connects a work or school account on Claude's Free, Pro, Max, Ultra, Team and Enterprise plans, and Anthropic's help article says it searches its calendar, and where an admin has enabled write tools creates, updates and deletes events and sends invitations. Read on 4 November 2026.
- Anthropic's security guide for its Microsoft 365 connector lists finding available meeting times among the tools of a work or school account. Read on 4 November 2026.
- Outlook Calendar, OpenAI's app for ChatGPT, reads and searches events and availability, and on a shared calendar it creates, updates, answers, cancels and deletes events where the permissions and actions they need are enabled. Read on 4 November 2026.
Connect it
Add it to
- 1Add to ClaudeOpens claude.ai - press Connect there.
- 2
Sign in, choose Outlook.com or Microsoft 365 and allow access at Microsoft in the window Claude opens. That adds your calendar and approves Claude in one step.
- 3
Ask Claude about your week
- 1
Run in Claude Code
/plugin marketplace add lumman-lab/multi-calendar/plugin install multi-calendar@multi-calendarRun the first, then the second.
- 2
Sign in, choose Outlook.com or Microsoft 365 and allow access at Microsoft on the Lumman page your browser opens. That adds your calendar and approves Claude Code in one step. If none opens, run /mcp and choose multi-calendar.
- 3
Ask, or run
/multi-calendar:week
Works fully on ChatGPT Business, Enterprise and Edu.
- 1
Copy the address
- 2Open ChatGPT plugins
Press +, choose Add custom MCP server, name it Multi Calendar, paste the address, choose OAuth, tick the box and press Create as a plugin.
- 3
Install it, then sign in, choose Outlook.com or Microsoft 365 and allow access at Microsoft on the Lumman page it opens. That adds your calendar and approves ChatGPT in one step. In a chat, type @ and choose Multi Calendar.
- 1
Add to
~/.cursor/mcp.json - 2
Sign in, choose Outlook.com or Microsoft 365 and allow access at Microsoft on the Lumman page Cursor opens. That adds your calendar and approves Cursor in one step.
Streamable HTTP, OAuth 2.1 with dynamic client registration. No key or client id.
- VS Code
Run MCP: Add Server, choose HTTP, paste the address and name it multi-calendar.
- Gemini CLI
gemini extensions install https://github.com/lumman-lab/multi-calendarIts first call opens Lumman's sign-in; /mcp auth multi-calendar opens it again.
- Antigravity
agy plugin install https://github.com/lumman-lab/multi-calendarRun /mcp, open multi-calendar_multi-calendar and choose Authenticate; approve on the Lumman page, then paste the code Antigravity shows back into it.
Free for every calendar you connect. Any number of booking pages and circles for $50 a year or $5 a month.
Reach and limits
- Find free time across it and every other calendar you add.
- Create, move and cancel events, and answer invitations.
- Share booking links and a booking page, run group polls, and find a time with the people in a circle.
- An event can show you as out of office, but Outlook makes no focus time.
If it refuses
- Microsoft granted no access. Either it was declined, or your organisation has to approve Lumman first.
Connection
- Reached through
- Microsoft Graph
- Permissions
- Calendars.ReadWrite, User.Read, offline_access - delegated
Your data
- Stored
- Microsoft's credential, encrypted under a key held outside the database
- Calendars
- No copy kept - read from the calendar on each call
- Removing it
- Disconnecting deletes our credential.
Tools
- Offered
- All 21
Everything else
Multi Calendar's address, sign-in, limits and every tool: Multi Calendar's technical details.