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

Annotations already cover the safety profile (readOnly, non-destructive, openWorld), so the bar is lower. The description still adds real context: the auth requirement ('Needs the user's Cotlet API key with access to this app') and the shape of what comes back, 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?

It is short and front-loads the summary before detail. The first sentence and the opening of the second ('RSVPs of an event' / 'Returns the RSVPs of one event') overlap somewhat, a minor redundancy that keeps it from a 5.

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 3-param, single-required-id read tool with no output schema, the description covers purpose, return contents, filtering and auth prerequisites. It is largely self-sufficient; only the relationship to sibling attendee tools 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 schema already documents cursor, status enum and event_id. The description's 'filter by status to see waitlist or no-shows' adds a bit of interpretive meaning to the status param, but nothing about cursor behavior or the event_id source beyond what the schema states.

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 states a specific verb+resource ('Returns the RSVPs of one event') and enumerates the payload (guests each member brings, answers, check-in status). It is clearly understandable on its own, but it never differentiates itself from siblings like meetup_list_members, meetup_update_attendee, or meetup_mark_attendance, so it stops short of a 5.

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 only implied: 'Filter by status to see the waitlist or the no-shows' hints at a scenario, and the API-key line states a prerequisite. There is no explicit when-to-use guidance and no comparison against the other attendee-facing Meetup tools (update_attendee, mark_attendance).

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