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

Annotations only declare it a safe read; the description adds the ordering ('oldest RSVP first'), the host-visibility scope, and non-obvious filter semantics ('going includes guests approved on a Guest Approval event'). That is real behavioral context beyond structured fields.

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?

Purpose is front-loaded and nearly every clause carries information (return fields, ordering, auth, routing). The telegraphic, article-less fragments ('Hosts only.', 'guest_id goes to...') read slightly clipped but waste little.

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 no output schema, the description carries the return-shape burden and does so explicitly: name, RSVP status, party size with plus-one names, check-in, RSVP note, questionnaire answers. Combined with annotations, nothing needed to call it correctly 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 3 is the floor; the description still adds value by clarifying what 'going' returns and where guest_id feeds downstream, plus noting that total counts filtered matches. It doesn't explain the cursor or checked_in interaction beyond the schema.

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+resource (guest list of an event) and enumerates the returned fields, so an agent knows exactly what it gets. It doesn't distinguish itself from the sibling list_past_guests, which is the one ambiguity left.

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?

Gives a clear access precondition ('Hosts only') and forwards to the right follow-up tools by naming approve_guests and check_in_guests for guest_id. It never says when to prefer list_past_guests instead, so it falls short of full when/when-not coverage.

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