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

Annotations only say it is a non-readonly, non-destructive, non-idempotent open-world write. The description adds the traits that actually matter: invites are emailed immediately on live autopilot events, the required permission differs by event state, and adding to a classic poll is rejected. That is real side-effect and prerequisite disclosure beyond the structured hints.

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 sentences, each carrying load: what it does, where it does it, and what is refused. No filler, no restating of the name or title, and the draft-vs-live distinction is 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?

With an output schema present, return values need no explanation, and the description covers target types, permission requirements, mailing side effects, and the refusal case. It could still say what happens when a guest already exists (update_guest territory) or note the 75-guest cap, which are the only meaningful gaps.

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 50%, and the description only elaborates on event_id (draft_ id vs live event id), which the schema already documents. The guests array — its 1-75 item bounds and the optional name/email/phone fields — is not explained in the description at all, so it does not compensate for the coverage gap.

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+resource (adds guests) and scopes it to exactly two target types: a draft_ id from create_event or a live AUTOPILOT event. It also rules out a third case (classic share-link polls), so an agent can distinguish this from siblings like update_guest or remove_guests without opening a schema.

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 clear conditions per target: a live autopilot event needs the send permission and mails invites, an unsent draft needs only write permission, and a classic poll is refused outright. It stops short of naming alternative siblings (update_guest, remove_guests, send_invites) for adjacent intents, so it is strong context rather than a full routing guide.

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