calendar_update

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

Annotations declare this is a write (readOnlyHint=false) but non-destructive and open-world, so the safety profile is already covered. The description adds real value beyond that: the ETag is concurrency control tied to the last read, implying stale-read rejection, and it discloses the hard limitation on recurring/attendee events. It does not say what error or state results from an ETag mismatch.

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?

Two tight sentences with no filler. The core action is front-loaded and the limitation follows immediately as a qualifier.

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?

For a mutation tool with no output schema and zero schema descriptions, the description covers the concurrency model and editability limits but leaves field formats, required-vs-optional update semantics, and failure behavior unaddressed. Adequate to start, incomplete to call confidently.

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 0% and the schema only lists fields (event_id, etag, start, end, title, location, description) with no semantic hints. The description explains the ETag's meaning (must be last-read) but says nothing about date/time formats, partial-update behavior of the nullable fields, or length limits.

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?

States a specific verb (Edit) and resource (standalone personal event) and narrows scope by excluding recurring events and attendee meetings, which effectively separates it from calendar_create/calendar_delete. It does not explicitly name the nearest sibling, calendar_update_draft, so an agent must infer that drafts use a different tool.

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?

Gives an explicit when-not condition (recurring events and attendee meetings are not editable in this release) and implies the precondition of having previously read the event, since the ETag must be the last-read one. No named alternative tool is offered for the excluded cases, so the routing is only partial.

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