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

The description says 'Idempotent: logging the same lounge on the same date updates the existing visit's rating/notes instead of creating a duplicate,' but the annotations set idempotentHint to false. This is a direct contradiction between the description and the structured annotation, so the agent cannot reliably know the tool's behavioral guarantees.

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?

Three concise sentences with no filler. The main action is front-loaded, the identification options are stated clearly, and the idempotency behavior is explained efficiently. Every sentence earns its place.

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?

The description covers identification keys, optional rating/notes, and same-date update behavior, but it does not explicitly state that a lounge identifier is required despite the input schema only making visited_at required. An agent could reasonably call with only visited_at and fail. The idempotency contradiction also leaves ambiguity, and no return behavior is described.

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 baseline is 3. The description adds useful relational semantics beyond the schema: the slug OR lounge_name + airport_iata identification alternatives, and that rating/notes are optional and update the existing same-date visit. This helps the agent understand how the parameters work together.

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 and resource: 'Log a lounge visit (check in).' It clearly distinguishes this from sibling review/update/delete tools by describing the check-in action and noting that logging the same lounge on the same date updates the existing visit instead of duplicating it.

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 gives clear usage context: when logging a visit, identify the lounge by slug or lounge_name + airport_iata, and optionally include rating/notes. The idempotency note tells agents that reusing the call on the same date updates rather than duplicates, but it does not explicitly name alternative tools or exclusions such as update_visit.

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