Add categories field to calendar-UpdateEvent (Calendar MCP write parity with mail)

Summary

The calendar-UpdateEvent MCP tool does not expose categories as a parameter, even though Microsoft Graph's PATCH /me/events/{id} fully supports writing categories and the Work IQ MCP already has a working OAuth client with Calendars.ReadWrite (the same client successfully reads categories today via ListCalendarView).

This blocks any "categorize my meetings" automation. There is no MCP path to write categories programmatically — every fallback we tried hit a tenant-policy wall.

Reproduce

1. Call calendar-UpdateEvent with any combination of supported parameters.
2. There is no categories parameter in the schema.
3. Even when categories is passed inline (in case the wrapper forwards unknown fields), it is dropped silently — no error surface.

Why fallback paths don't work for Microsoft corp tenant users

Trying to bypass the wrapper and hit Graph directly is blocked at every layer for users on the microsoft.com tenant:

The only realistic unblock is exposing categories directly in the MCP, since the MCP already has the right OAuth client with the right scope.

Requested change

Add an optional categories parameter (array of strings) to:

• calendar-UpdateEvent
• (parity) microsoft-outlook-calendar-UpdateEvent if separate

Behavior matches Graph: categories is the full list, replacing the existing array. Callers that want to preserve existing categories should GET first, merge, and PATCH. (Or expose categoriesToAdd / categoriesToRemove for additive semantics — either works.)

Code change scope

Wrapper-only change. The underlying Graph endpoint and required permission (Calendars.ReadWrite) are already covered by the MCP's existing OAuth client. No new consent, no new scope, no new auth flow.

Use cases unblocked

• 8-category taxonomy auto-tagging (Will's calendar-categorize skill)
• Project-call labeling for ADO weekly reports
• Deep-focus auto-tagging
• Shiproom-prep sweeps
• Any plugin that wants to apply categories programmatically

mail-UpdateMessage already exposes categories; calendar parity is a reasonable expectation.

Workaround in place today

Manual right-click in Outlook. Defeats the automation.

Start by locating the calendar-UpdateEvent MCP tool schema and compare it with mail-UpdateMessage, which already exposes categories. Add the optional string-array parameter to the calendar tool, then verify that it is forwarded as the full categories list in an update request; check the separate microsoft-outlook-calendar-UpdateEvent tool if present.