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

Annotations cover the safety profile (idempotent, non-destructive, not read-only, closed-world), and the description adds substantial context beyond them: the write permission requirement, the fact that no mail is sent, the draft-id refusal, and the precedence rule when both inputs are given. That is exactly the extra behavioral detail the annotations cannot carry.

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 dense sentences, front-loaded with the core action, followed by input-combination rules and then the permission/no-mail constraints. Every clause carries information; the mid-sentence dash constructions are slightly packed but not wasteful.

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, the description need not explain return values, and it covers the remaining ground: identity of the actor, valid event state, input combination semantics, permission requirement, and notification side effects. Nothing an agent needs to call it correctly is missing.

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 100%, so the baseline is 3, but the description adds meaning the schema lacks: the precedence rule ('a per-date answer wins for the dates it names') and the combined use of all+responses. It does not expand on the yes/maybe/no enum, but that is self-evident.

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 ('marks the organizer's own availability') and immediately distinguishes it from the sibling respond_to_poll by noting it is 'the same vote a personal link submits' but scoped to the organizer's own poll. An agent can identify the operation and its boundary without opening the 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 when-to-use context (organizer is a participant on their own poll) and an explicit when-not ('a draft_ id is refused — vote after sending'). It does not name respond_to_poll directly as the alternative for guests, but the personal-link framing implies the split.

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