update-calendar-event

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

Annotations already indicate destructiveHint=true and readOnlyHint=false, so the description's mutation nature is covered. The description adds valuable behavioral detail beyond annotations, specifically the attendee replacement behavior ('Setting attendees replaces the entire attendee list — include all attendees, not just new ones'). This is a critical side effect that could cause data loss. It also offers tips like using list-users, which contextualizes behavior. No contradictions 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.

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

The description is concise, with the core purpose stated in the first sentence, followed by a compact tips section. The critical tips are highlighted with emojis and uppercase 'CRITICAL' and 'WARNING', making them stand out. There is no fluff; every sentence earns its place. It could be slightly more structured, but it is well within appropriate length and front-loaded.

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

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

Given the tool's complexity (large nested body schema, destructive hint, no output schema), the description provides some critical context (attendee replacement) but omits other important guidance. It does not explain partial update semantics (whether sending only some properties leaves others unchanged) or the need for eventId as a path parameter, though that is in the schema. It also does not mention the confirm parameter, which is crucial for destructive operations when the confirm gate is enabled. The tip about list-users is helpful, but overall the description is not fully comprehensive for a mutation tool of this complexity.

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

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

Schema description coverage is 80%, so most parameters are already documented in the schema. The description adds value for the attendees parameter by explaining its replacement semantics, which is not in the schema (schema only says 'The collection of attendees for the event.'). It also indirectly references the emailAddress field. This is a modest enhancement beyond the schema, but it does not address other parameters like confirm, eventId, or includeHeaders, which are explained in the schema. Baseline of 3 is appropriate since the schema does the heavy lifting.

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

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

The description states a clear verb and resource: 'Update the properties of the event object.' However, it does not distinguish from sibling tools like update-specific-calendar-event, which also updates a calendar event. The name 'update-calendar-event' implies a general update, but the description leaves which specific event is targeted ambiguous without reference to the eventId parameter. This is clear but not fully differentiated.

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

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

The description provides critical usage guidance: it warns against guessing recipient emails and instructs to use list-users, and explicitly warns that setting attendees replaces the entire list. This helps the agent avoid common mistakes. However, it does not explain when to choose this tool over alternatives like update-specific-calendar-event, nor does it mention any prerequisites or context for normal use. The guidance is useful but incomplete for full selection.

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