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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: the exact payload fields returned and an explicit negative guarantee ('never attendee or RSVP lists'), which prevents the agent from calling this hoping to get attendance data.

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?

Two sentences, both front-loaded with the essential fact first (what it fetches) and the constraint second (what it won't return). No filler, no restatement of the title.

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?

One required parameter, no output schema, and the description compensates by enumerating the returned fields and excluding attendee data. Only gap is the absence of any error/not-found behavior, which is minor for a read-only single-record lookup.

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 baseline is 3, but the description adds real meaning the schema does not: it explains how to derive the value from a meetup.com event URL (the trailing number) and gives a sample value. That is practical disambiguation beyond 'The event's numeric Meetup ID'.

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 full details') and a scoped resource ('one Meetup event by its numeric ID'), which cleanly separates it from the plural siblings meetup_search_events and meetup_group_events. An agent knows immediately this is a single-record lookup, not a listing.

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 by 'by its numeric ID' — call it when you already have an event ID — but no sibling is named and there is no explicit when-not guidance (e.g., 'use meetup_search_events if you only have a keyword or URL slug'). Adequate but leaves routing to inference.

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