Update an event

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

Annotations declare non-read-only, non-destructive, non-idempotent, so the safety profile is already covered; the description still adds genuinely useful behavior beyond that by explaining patch semantics ("only the fields you supply are modified") and the account-scoping requirement for ids. It omits the default notification behavior, but the schema's send_updates description carries that.

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?

Three short sentences, front-loaded with the action and then the two most important behavioral facts. No filler, though the account sentence partially duplicates the schema text rather than earning new ground.

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 an 11-parameter partial-update tool with no output schema, the description supplies the two things an agent most needs to call it safely: patch semantics and the account requirement. Combined with annotations covering the safety profile and the schema covering defaults, this is adequate for correct invocation.

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 coverage is 55%, so several parameters (end, title, location, description, event_id) are undocumented in both places. The description adds the semantics that unspecified fields are untouched and that account is mandatory due to account-scoped ids, but that largely echoes the schema's own account description; it does not compensate for the coverage gap on the remaining fields.

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 and resource ("Change fields on an existing event") and clarifies that this is a partial update, which distinguishes it from create_event/delete_event. It does not, however, explicitly separate itself from the sibling move_event, which also alters event fields, so an agent must infer the boundary.

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 gives clear usage context for the partial-update behavior and states the account prerequisite, but offers no when-to-use/when-not guidance relative to siblings like move_event or update_routine. Usage is implied rather than routed.

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