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

No annotations are provided, so the description carries the full behavioral disclosure burden. It transparently discloses that prices are cached, not real-time, and that booking links contain a Travelpayouts referral code with the operator earning a commission while prices remain identical. It also mentions that results include agent_display markdown ready to pass to the user. This goes beyond a minimal description.

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 description is fairly concise but contains duplication: the Portuguese phrase 'Busca as passagens aéreas mais baratas conhecidas' is repeated in English as 'Search cheapest known fares.' The information is front-loaded with the primary purpose and then adds behavioral details. It is not overly long, though the repetition could be trimmed.

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?

Given the tool's complexity (9 params, no output schema), the description covers the main contextual points: it explains cached availability, the agent_display output format, and the referral mechanism. It does not explicitly state that it is a read-only operation, but that is implied. Missing guidance on error handling or pagination is minor since the schema covers parameters. Overall, it is reasonably complete for an agent to call it correctly.

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 description coverage is 100%, so all 9 parameters are already documented in the schema. The description does not add additional parameter-level meaning beyond what the schema provides. The mention of accepting city names and resolving them automatically is already present in the origin/destination parameter descriptions, so the description adds no extra semantic value.

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 clearly states the tool's function—searching for the cheapest known airfares between two points, using cached prices from Aviasales/Travelpayouts rather than real-time availability. It also mentions that it accepts Portuguese city names. The purpose is specific and includes a verb and resource, but it does not explicitly differentiate itself from sibling tools like cheapest_route, which likely has a similar function.

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 provides context (cached fares, not real-time, returns agent_display markdown) but does not explicitly state when to use this tool versus alternatives like cheapest_route or price_calendar. The mention of 'preços em cache' hints that real-time queries should go elsewhere, but no explicit comparison or exclusion is made.

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