owa-mcp

A Model Context Protocol (MCP) server that gives Claude Code full access to your Microsoft Outlook calendar and email — without requiring an Azure app registration.

How it works

Microsoft Outlook Web (outlook.office.com) runs inside a Playwright-controlled headless Microsoft Edge browser that uses your existing, signed-in Edge profile. When Outlook Web loads, it issues Bearer tokens for its own internal API calls. This server intercepts those tokens and reuses them against the outlook.office.com/api/v2.0 REST endpoint.

The result: full Calendars.ReadWrite and Mail.ReadWrite scope with no OAuth app registration, no client ID, and no IT involvement — as long as you are already signed in to Microsoft 365 in your Edge browser.

Tokens expire after ~80 minutes. The server refreshes automatically by re-launching the headless browser in the background.

Why this approach

Many enterprise Microsoft 365 tenants enforce Conditional Access policies that block third-party OAuth flows (e.g., Azure CLI, custom app registrations). Managed devices may restrict which apps can authenticate. The browser-session interception approach works because it piggybacks on an authentication flow that already satisfies all policy requirements — the same one used by Outlook Web itself.

Prerequisites

• macOS (tested on macOS 15)
• Microsoft Edge installed at /Applications/Microsoft Edge.app
• Signed in to Microsoft 365 in Edge (open Edge, go to outlook.office.com, confirm you see your calendar)
• Node.js 20+

Installation

claude mcp add owa -s user -- npx owa-mcp

That's it. Restart Claude Code — you should see calendar tools available.

<details> <summary>Manual installation (alternative)</summary>

git clone https://github.com/benpeter/owa-mcp
cd owa-mcp
npm install
npm run build
claude mcp add owa -s user -- node /absolute/path/to/owa-mcp/dist/index.js

</details>

Available Tools

get_calendar_events

Returns calendar events in a time range.

Parameter	Type	Required	Description
startDateTime	string	yes	ISO 8601 start
endDateTime	string	yes	ISO 8601 end
maxResults	number	no	Max events (default 50, max 100)
timezone	string	no	IANA timezone (default UTC)

create_calendar_event

Create a new event. Adding attendees auto-sends invitations.

Parameter	Type	Required	Description
subject	string	yes	Event title
startDateTime	string	yes	Local datetime without offset
endDateTime	string	yes	Local datetime without offset
timezone	string	no	Windows timezone name (default "W. Europe Standard Time")
body	string	no	Event description
location	string	no	Location name
attendees	array	no	[{ email, name?, type? }] — sends invitations
isAllDay	boolean	no	All-day event
showAs	string	no	Free, Tentative, Busy, Oof, WorkingElsewhere
isOnlineMeeting	boolean	no	Create as Teams meeting
hideAttendees	boolean	no	Hide attendee list from other attendees (default false)
responseRequested	boolean	no	Request RSVPs from attendees (default true)
reminderMinutes	number	no	Reminder minutes before start. Omit for Outlook default, 0 to disable
recurrence	object	no	Make this a recurring event. See Recurrence below

update_calendar_event

Update fields on an existing event. Only include fields to change.

Parameter	Type	Required	Description
eventId	string	yes	Event ID
subject	string	no	New title
startDateTime	string	no	New start time
endDateTime	string	no	New end time
timezone	string	no	Timezone for start/end
body	string	no	New body (caution: overwrites Teams join link)
location	string	no	New location
showAs	string	no	New show-as status
isPrivate	boolean	no	Mark as private
hideAttendees	boolean	no	Hide attendee list from other attendees
responseRequested	boolean	no	Request RSVPs from attendees
reminderMinutes	number	no	Reminder minutes before start. 0 to disable
recurrence	object	no	Change the recurrence pattern. Only applies to series master events. See Recurrence below

cancel_calendar_event

Cancel a meeting you organized. Sends cancellation with reason to attendees. Supports recurring series operations.

Parameter	Type	Required	Description
eventId	string	yes	Event ID
reason	string	no	Cancellation reason sent to attendees
scope	string	no	single (default), thisAndFollowing, or allInSeries

delete_calendar_event

Remove an event from your calendar silently (no notification sent). Supports recurring series operations.

Parameter	Type	Required	Description
eventId	string	yes	Event ID
scope	string	no	single (default), thisAndFollowing, or allInSeries

respond_to_calendar_event

RSVP to a meeting: accept, tentatively accept, or decline. Uses OWA's internal service.svc API when possible, which works even when the organizer has disabled response requests (ResponseRequested: false). Falls back to the standard REST API if the internal API can't resolve the event.

Parameter	Type	Required	Description
eventId	string	yes	Event ID
response	string	yes	accept, tentative, or decline
comment	string	no	Message to organizer
sendResponse	boolean	no	Notify organizer (default true)
proposedStartDateTime	string	no	Propose alternative start (tentative/decline only)
proposedEndDateTime	string	no	Propose alternative end

follow_calendar_event

Track an event on your calendar without RSVPing. Shows as Free, organizer not notified.

Parameter	Type	Required	Description
eventId	string	yes	Event ID
comment	string	no	Optional message included in the follow notification to the organizer
timezone	string	no	Timezone for returned event

get_series_master

Inspect the master event of a recurring series. Returns recurrence pattern, cancelled occurrences, and full event details. Accepts any event ID from the series.

Parameter	Type	Required	Description
eventId	string	yes	Any event ID from the series (resolved automatically)
timezone	string	no	IANA timezone (default UTC)

list_series_instances

List all occurrences of a recurring series within a date range. Accepts any event ID from the series.

Parameter	Type	Required	Description
eventId	string	yes	Any event ID from the series (resolved automatically)
startDateTime	string	yes	ISO 8601 start
endDateTime	string	yes	ISO 8601 end
timezone	string	no	IANA timezone (default UTC)

list_mail_folders

List all mail folders in the mailbox, or child folders of a specific folder.

Parameter	Type	Required	Description
parentFolderId	string	no	List children of this folder. If omitted, lists top-level folders

get_emails

Get emails from a specific mailbox folder with optional filtering.

Parameter	Type	Required	Description
folderId	string	no	Folder ID or well-known name (Inbox, Drafts, SentItems, DeletedItems). Default: Inbox
filter	string	no	all, unread, flagged, today, this_week
limit	number	no	Max results (default 20, max 500)
pageToken	string	no	Pagination token from previous response

search_emails

Search emails using full-text query OR structured filters (mutually exclusive).

Parameter	Type	Required	Description
query	string	no	Full-text search query. Cannot combine with structured filters
from	string	no	Filter by sender email
subject	string	no	Filter by subject (contains)
receivedAfter	string	no	ISO 8601 datetime
receivedBefore	string	no	ISO 8601 datetime
folderId	string	no	Scope search to folder
limit	number	no	Max results (default 20, max 500)

get_email

Read a single email with full body content and attachment metadata.

Parameter	Type	Required	Description
messageId	string	yes	Message ID
format	string	no	text (default) or html

get_attachment

Download an email attachment to disk.

Parameter	Type	Required	Description
messageId	string	yes	Message ID
attachmentId	string	yes	Attachment ID from get_email response

send_email

Compose and send a new email in one step. For more control, use create_draft + update_draft + send_draft.

Parameter	Type	Required	Description
to	array	yes	[{ email, name? }]
subject	string	yes	Subject line
body	string	yes	Body content
bodyType	string	no	text (default) or html
cc	array	no	CC recipients [{ email, name? }]
bcc	array	no	BCC recipients
importance	string	no	Low, Normal (default), High
saveToSentItems	boolean	no	Save to Sent Items (default true)

create_draft

Create a new email draft saved to Drafts folder.

Parameter	Type	Required	Description
to	array	yes	[{ email, name? }]
subject	string	yes	Subject line
body	string	yes	Body content
bodyType	string	no	text (default) or html
cc	array	no	CC recipients
bcc	array	no	BCC recipients
importance	string	no	Low, Normal (default), High

create_reply_draft

Create a draft reply to the sender. Returns draft with pre-filled recipients, quoted body, "RE:" subject.

Parameter	Type	Required	Description
messageId	string	yes	Message ID

create_reply_all_draft

Create a draft reply-all. Returns draft with all original recipients, quoted body, "RE:" subject.

Parameter	Type	Required	Description
messageId	string	yes	Message ID

create_forward_draft

Create a draft forward. Returns draft with quoted body, "FW:" subject, no To recipients.

Parameter	Type	Required	Description
messageId	string	yes	Message ID

update_draft

Modify a draft before sending. Can change subject, body, recipients, importance.

Parameter	Type	Required	Description
messageId	string	yes	Draft message ID
subject	string	no	New subject
body	string	no	New body content
bodyType	string	no	text or html
toRecipients	array	no	Replace all To recipients
ccRecipients	array	no	Replace all CC recipients
bccRecipients	array	no	Replace all BCC recipients
importance	string	no	Low, Normal, High

send_draft

Send a draft message. Moves from Drafts to Sent Items.

Parameter	Type	Required	Description
messageId	string	yes	Draft message ID

move_email

Move a message to a different folder. Returns the moved message (with updated ID).

Parameter	Type	Required	Description
messageId	string	yes	Message ID
destinationId	string	yes	Folder ID or well-known name (Inbox, Drafts, SentItems, DeletedItems, Archive)

delete_email

Delete a message (moves to Deleted Items).

Parameter	Type	Required	Description
messageId	string	yes	Message ID

update_email

Update email properties: mark as read/unread, flag/unflag.

Parameter	Type	Required	Description
messageId	string	yes	Message ID
isRead	boolean	no	Set read (true) or unread (false)
flagStatus	string	no	NotFlagged, Flagged, or Complete

Example prompts:

• "What meetings do I have next week?"
• "Create a 30-minute meeting with Jane tomorrow at 2pm"
• "Decline the ECCN sync with a note that I'm on vacation"
• "Follow the Analytics Tech Call so I can see it on my calendar"
• "Cancel all future occurrences of the weekly sync starting from next week"
• "What's the recurrence pattern for the Monday standup?"
• "Create a weekly team sync every Tuesday at 10am for the next 3 months"
• "Show me unread emails from today"
• "Reply to that email from Sarah and add Bob to CC"
• "Forward the Q3 report to the finance team"
• "Mark all emails from the newsletter as read"

Recurrence Object

Used by create_calendar_event and update_calendar_event to define recurring events.

{
  "recurrence": {
    "pattern": {
      "type": "weekly",
      "interval": 1,
      "daysOfWeek": ["Monday", "Wednesday", "Friday"]
    },
    "range": {
      "type": "endDate",
      "startDate": "2026-04-07",
      "endDate": "2026-07-07"
    }
  }
}

Pattern types: daily, weekly, absoluteMonthly, relativeMonthly, absoluteYearly, relativeYearly

Pattern Field	Type	Description
type	string	Required. Pattern type
interval	number	Required. Interval between occurrences (1 = every, 2 = every other)
daysOfWeek	string[]	Days for weekly/relative patterns
dayOfMonth	number	Day of month for absoluteMonthly/absoluteYearly
month	number	Month (1-12) for yearly patterns
index	string	Week index for relative patterns: first, second, third, fourth, last
firstDayOfWeek	string	First day of week (default Sunday)

Range types: endDate, numbered, noEnd

Range Field	Type	Description
type	string	Required. How the series ends
startDate	string	Required. Series start (YYYY-MM-DD)
endDate	string	End date (required for endDate type)
numberOfOccurrences	number	Count (required for numbered type)
recurrenceTimeZone	string	Timezone for recurrence dates

Troubleshooting

Token acquisition times out Open Edge, navigate to outlook.office.com, confirm you can see your calendar. The session may have expired — sign in again.

ErrorAccessDenied on calendar API The intercepted token didn't carry calendar scope. This is rare; try quitting all Edge windows and restarting.

Headless browser opens a visible window This shouldn't happen normally. If it does, check that no other Playwright process is holding the Edge profile directory lock.

License

Apache 2.0 — see LICENSE.