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

Annotations already declare readOnlyHint: true, and the description reaffirms 'Read-only' without contradiction. Beyond that, it adds behavioral context about what information the tool provides (attendance counts, statuses), which helps the agent predict the response type even though an output schema exists. This adds value beyond the annotation.

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?

The description is concise, with the core usage scenario front-loaded, followed by the alternative and read-only note. Every sentence earns its place; no wasted words.

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 are covered. The description covers the primary use cases, the sibling alternative, and read-only nature. It lacks explicit guidance on the event_id parameter, but that is a minor gap given the tool's simplicity and the clear naming convention.

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?

The schema has a single parameter (event_id) with 0% description coverage. The description does not explain what event_id is, how to obtain it, or any constraints beyond the schema's minLength. Since the coverage is low, the description should compensate but doesn't, leaving the parameter's semantics to inference from the name.

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 clearly states the tool's purpose: summarizing RSVP responses (who responded, counts of attendees, adults/children, non-respondents) for a Lemonvite invitation. It distinguishes itself from per-guest detail and names the sibling for that purpose, making the scope explicit.

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 explicit when-to-use criteria ('when the user asks who has responded, how many people are attending...') and directly names the alternative tool for per-guest detail (lemonvite_list_guests), with a clear condition for choosing it. No ambiguity remains.

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