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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the description's increment is the partial-update rule ("Omitted dates remain unchanged"), which is genuinely useful for a destructive write. It does not explain why the operation is flagged destructive (overwriting an existing vote), nor any permission or rate constraints, so the added behavioral context is real but thin.

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?

Four sentences, each carrying actionable content, with the core operation front-loaded before the autonomy and update guidance. The final "omitted dates remain unchanged" sentence is well placed; nothing is padding, though "Change responses when…" mildly restates the opening verb.

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 destructive, open-world write with four required identifiers and no output schema, the description covers intent and partial-update semantics but omits what the identifiers refer to and what a successful call returns or how failures surface. Adequate to attempt a call, not complete enough to call confidently with unfamiliar IDs.

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% across 5 parameters, so the description carries the full burden. It explains only the `responses` array in spirit ("one or more proposed dates", yes/maybe/no) and says nothing about `eventId`, `participantId`, `requestId`, or `agent` — the latter two are especially opaque given requestId's length bounds and agent's empty-string default.

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 names a specific verb set ("Set or change") and a specific resource ("your yes/maybe/no response to one or more proposed dates"), which clearly frames a per-date RSVP operation. It does not, however, differentiate itself from the sibling `vote` tool, leaving a plausible ambiguity an agent must resolve on its own.

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?

It gives concrete operating guidance: check accessible calendars, respond autonomously without per-vote approval, use "maybe" for uncertainty, and re-vote when the human vetoes or circumstances change. There is no explicit when-not-to-use clause or pointer to `vote`/`propose_date` as alternatives, which keeps it below a 5.

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