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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds useful behavioral context: exactly what aggregates are returned and the auth requirement ('Needs the user's Cotlet API key with access to this app'), which the annotations do not convey.

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 first two sentences substantially restate the same content ('attending, declined and pending counts...' then 'counts of guests who are attending, declined or have not responded...'), which is redundant padding. The auth note is a distinct, useful addition, but the description could be cut nearly in half.

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 read-only reporting tool with full schema coverage and no output schema, the description explains the returned aggregates and the auth prerequisite, which is enough for an agent to call it correctly. Only the lack of explicit routing guidance against sibling list tools is a gap.

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% and the single event_id parameter is already documented as coming from list_events, so the schema carries the load. The description adds no additional parameter meaning, making the baseline 3 correct.

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 (get) and resource (RSVP summary) and describes the shape of the output: attending/declined/pending counts plus per-question answer breakdown. An agent can tell it is an aggregate report rather than a raw guest list, though it never explicitly contrasts with siblings like joy_list_guests.

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?

Usage is implied (pull RSVP tallies for an event) but there is no explicit when-to-use, when-not-to-use, or named alternative. The 'matches the Guest List screen' note gives some context for trusting the numbers but does not guide tool selection.

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