update_event

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

Annotations declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, which covers the safety profile. The description adds the key partial-update semantic ('Only provided fields are changed'), which is beyond what annotations convey. But it doesn't disclose what happens on missing event_id, whether attendees replace or merge, or timezone handling.

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 concise sentences that front-load the purpose and add the partial-update semantic. Zero wasted words. Could arguably add a usage hint, but as written it's efficient and clear.

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?

An output schema exists, so return values are covered. The partial-update behavior is stated. However, for a mutation tool updating an event, the description doesn't clarify interaction with list_events/get_event for finding the event, doesn't mention timezone handling, and doesn't flag that attendees replacement semantics may be surprising. Could be slightly more complete.

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 100%, with each parameter having its own description ('New start time (ISO 8601)', 'New event title', etc.). The description emphasizes the 'only provided fields changed' semantics, which clarifies the null/default field behavior encoded in the schema. Baseline 3 is appropriate since the schema carries the load.

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 uses specific verb+resource ('Update an existing calendar event') and adds value by stating that 'Only provided fields are changed', which clarifies partial update behavior. However, it doesn't explicitly distinguish it from siblings like create_event, though the name and verb largely make this clear.

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 no guidance on when to use this tool vs siblings (create_event, delete_event, quick_add). It doesn't mention that the full event object exists elsewhere or that modifications affect only the calendar specified by calendar_id. No exclusions or context for choosing it over alternatives.

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