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cancel-calendar-event

cancel-calendar-event
Destructive

Organizers cancel meetings and notify attendees with a custom message. Attendees cannot cancel; they should decline instead.

Instructions

This action allows the organizer of a meeting to send a cancellation message and cancel the event. The action moves the event to the Deleted Items folder. The organizer can also cancel an occurrence of a recurring meeting by providing the occurrence event ID. An attendee calling this action gets an error (HTTP 400 Bad Request), with the following error message: 'Your request can't be completed. You need to be an organizer to cancel a meeting.' This action differs from Delete in that Cancel is available to only the organizer, and lets the organizer send a custom message to the attendees about the cancellation.

šŸ’” TIP: Cancels a meeting (organizer only) and sends a cancellation message to all attendees. Body: { Comment (optional string, custom message) }. Use this instead of delete-calendar-event when you want attendees to see 'Canceled' in their calendar. Attendees calling this get HTTP 400 — they should use decline-calendar-event instead.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
bodyYes
confirmNoFor destructive operations when the confirm gate is enabled (MS365_MCP_REQUIRE_CONFIRM=true; off by default). Set to true only after the user has explicitly approved this action. When the gate is on, calls without confirm: true return { error: "confirmation_required" } without touching user data.
eventIdYesValue for the 'eventId' path segment. Pass it under the name 'eventId', not as 'id'. Use the 'id' field of the event object as returned by Microsoft Graph.
includeHeadersNoInclude response headers (including ETag) in the response metadata
excludeResponseNoExclude the full response body and only return success or failure indication
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations indicate destructive and not read-only. The description adds beyond annotations: moves event to Deleted Items, sends custom message, only organizer succeeds, recurrence handling via occurrence ID. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured with key purpose first, then details, then a tip. Slightly verbose but front-loaded and every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given no output schema, the description covers outcomes (cancellation message, event moved to Deleted Items), error cases, recurrence, and prerequisites (organizer only). Complete for agent usage.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is high (80%). Description clarifies that body has optional Comment string and explains eventId usage. The tip repeats parameter info but adds value by summarizing body structure.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool cancels a meeting for the organizer only and sends a cancellation message. It distinguishes from delete-calendar-event by explaining that cancel shows 'Canceled' in attendees' calendars, and notes that attendees calling get a 400 error and should use decline-calendar-event.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly tells when to use this tool vs alternatives: 'Use this instead of delete-calendar-event when you want attendees to see Canceled' and advises attendees to use decline-calendar-event. It also clarifies it is for organizers only.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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