How to Connect Multiple Outlook Calendars to Claude Cowork
Claude Cowork holds one Microsoft identity, will not book on any calendar that is not your own, and cannot connect a personal Outlook.com address at all. Connect every Microsoft account to Carly, add Carly to Claude once, and a single Cowork task can read or book on whichever calendar you name. Carly holds your Google calendars and every mailbox on both sides in the same place, so this setup covers the rest of what you own.
What the finished setup gives you
With one Carly connector in Cowork, you can:
- compare a work calendar and a personal one in the same question;
- book on the account that owns the meeting;
- put an event on a calendar a colleague shared with you;
- hold a client tenant alongside your own without either dropping off;
- clear a room and an executive’s diary in one pass;
- keep it running when an invite lands and nobody is watching.
The accounts stay separate underneath. Carly supplies the routing, and Claude remains where you run the task.
Why the native Microsoft 365 connector does not solve this
Cowork has no connector catalogue of its own. Anthropic documents that Cowork supports the same extensibility features as other Claude products, managed from Customize, and synced when a session starts. There is no standalone Outlook Calendar connector; calendar arrives inside Microsoft 365, alongside mail and files.
Reading is genuinely broad. The read tools are outlook_calendar_search and find_meeting_availability, and Anthropic’s published permission set includes both Calendars.Read and Calendars.Read.Shared. Your secondary calendars, a bookable room, and a colleague’s calendar shared to you are all readable with no per-calendar setup.
Booking is where it stops. The write tools are outlook_create_event, outlook_update_event, outlook_delete_event, and outlook_respond_to_event, and the published permission set includes Calendars.ReadWrite while omitting Calendars.ReadWrite.Shared. Microsoft’s Graph reference defines the first as covering the signed-in user’s own calendars and the .Shared variant as the one extending to delegate and shared calendars. So Claude can read an executive’s diary and the room calendar, and put nothing on either. No amount of admin approval adds a permission the set does not request.
Three more gates sit on top:
- A personal Outlook.com address cannot connect. The connector requires a Microsoft Entra tenant on a Microsoft Business plan, and Anthropic states that
@outlook.com,@hotmail.com, and@live.comaddresses cannot be used. The common setup, personal plus work, is one connection and nothing. - Writes need consent, once per tenant. An Entra Global Administrator has to approve the expanded permission set. A consultant booking inside a client tenant needs that client’s own administrator.
- Calendar writes can never be pre-authorized. Anthropic states that “Always allow” is not supported for
outlook_create_eventoroutlook_update_event. A human confirms every event, so an unattended run can find tomorrow’s double booking and cannot fix it.
Connecting a second Microsoft identity replaces the first.
1. Sort your calendars
| Calendar | Owner | Native path in Cowork |
|---|---|---|
| Your work calendar | Your Microsoft 365 identity | Yes, read and write |
| Your secondary calendars | Same mailbox | Yes, read and write |
| A colleague’s calendar shared to you | Same tenant, different mailbox | Read only |
| A room or resource calendar | Same tenant | Read only |
| A personal Outlook.com calendar | Personal Microsoft account | No, cannot connect |
| A second employer or client tenant | Another tenant | Not at the same time |
2. Connect the first Microsoft account to Carly
- Sign in at carlyassistant.com.
- Open carlyassistant.com/integrations.
- Find Outlook and click Connect.
- Authorize the first Microsoft identity.
- Confirm the address in Carly’s connected list.
3. Add every other Microsoft account
- Return to Carly’s integrations page.
- Select Outlook → Connect again.
- Sign out of the preselected Microsoft session, or use a private window, so the next identity’s sign-in appears.
- Repeat for every additional account, personal Outlook.com and client tenants included.
- Verify each address after authorizing it.
Unlimited connected calendars are included, so a second or third Microsoft account is not a per-account charge.
4. Connect Carly to Claude Cowork
In Claude:
- Open Customize in the sidebar.
- Select Connectors.
- Click +, then Add custom connector.
- Paste
https://carlyassistant.com/mcp/. - Click Add and authorize your Carly account.
- In the Cowork task, open + → Connectors and enable Carly.
Anthropic documents this path in its remote MCP connector guide. Connectors sync at session start, so a connection added mid-session may need a fresh one.
5. Test each calendar read-only
One calendar per prompt until routing is reliable. Priya below is a fictional colleague:
On my work calendar, list everything scheduled between Tuesday and Thursday next week. Read only.
On the calendar Priya shares with me, find the first two hours she has free after Wednesday lunchtime. Do not book anything.
Then the question that needed two accounts:
Compare my work calendar and my personal calendar for next week and list every clash, showing which account each event came from.
6. Reuse this routing prompt
Treat my Microsoft 365 account as Work and my Outlook.com account as Personal. Always name the target calendar and account before creating, moving, or cancelling an event. Never write to a calendar I have not named.
Then name the target per action:
Book the client review on the Work calendar on Thursday at 10, and block the school run on the Personal calendar every weekday at 3.
Native Cowork versus Carly
| Need | Claude Cowork | Carly connector |
|---|---|---|
| Read several calendars in one work mailbox | Yes | Yes |
| Read a calendar shared to you | Yes | Yes |
| Book on your own work calendar | Yes, after admin consent | Yes |
| Book on a shared or delegated calendar | No | Yes |
| Connect a personal Outlook.com calendar | No | Yes |
| Hold two Microsoft identities at once | No | Yes |
| Act when an invite lands | No | Yes |
Inside one consenting tenant, on your own calendar, Cowork does the job well: it runs long multi-step tasks against real documents, and the read tools are accurate enough that availability questions come back right.
The gaps are structural rather than fixable, and the trigger is the sharpest. Cowork’s scheduled tasks run hourly, daily, weekly, on weekdays, or on demand, which is a clock rather than an event, and Anthropic documents the connector as on-demand rather than searching in the background. An invitation arriving starts nothing.
Carly holds several Microsoft identities at once, books on the one you name including calendars shared to you, and fires when the invite lands. Carly offers free Zapier-style workflows; AI agents start at $35/month.
Quick fixes when a calendar does not appear
| Problem | Fix |
|---|---|
| Cowork will not connect your Outlook.com address | That is a personal Microsoft account, which the connector rejects. Connect it to Carly instead |
| Every calendar tool comes back read-only | Write tools need one-time Entra Global Administrator consent for the tenant |
| Claude reads a colleague’s calendar but will not book on it | The published permission set omits Calendars.ReadWrite.Shared, so route the booking through Carly |
| A scheduled task spots a clash and leaves it | Event creates and updates cannot be pre-authorized natively, so each one waits for you |
| Connecting a client tenant dropped your own account | One Microsoft identity at a time on the native connector. Keep both in Carly |
Frequently asked questions
Can Claude Cowork connect two Outlook calendars?
It connects one Microsoft 365 identity and reads every calendar that identity can already see, including shared ones. Two separate Microsoft accounts is where it stops, because connecting the second replaces the first.
Can Claude Cowork add events to a shared Outlook calendar?
No. Anthropic’s published permission set includes Calendars.Read.Shared for reading and Calendars.ReadWrite for writing, but not Calendars.ReadWrite.Shared, which is the Microsoft Graph permission covering delegate and shared calendars.
Why can’t I connect my Outlook.com account to Claude?
The Microsoft 365 connector requires a Microsoft Entra tenant on a Microsoft Business plan. Anthropic states that personal Microsoft accounts, including @outlook.com, @hotmail.com, and @live.com, cannot be used to connect.
Can a scheduled Cowork task book meetings overnight?
Not on the native connector. Anthropic states that “Always allow” is not supported for creating or updating calendar events, so every write pauses for a human.
Does Claude Cowork react when a meeting invite arrives?
No. Cowork’s scheduled tasks run on a clock, hourly through weekly or manually, and the connector is documented as on-demand rather than searching in the background.
Related: What is Claude Cowork · Multiple Outlook calendars in Claude · Multiple Google Calendars in Claude Cowork · Best AI assistants for Outlook Calendar
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