search_flights

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

Beyond the readOnlyHint/openWorldHint annotations, it discloses that results are sorted cheap-to-expensive, that round-trip prices cover the whole journey, and critically that prices come from a ~48h Aviasales cache rather than a live search, with the url as the source of truth. This is exactly the kind of non-obvious behavior an agent needs before presenting prices as current.

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 tight sentences that front-load the core purpose, then add pricing semantics and the cache caveat. No filler, though the round-trip/one-way point is split across sentences rather than consolidated.

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 7-parameter read-only search with no output schema, the description covers purpose, ordering, pricing scope, and the freshness limitation. The main missing piece is routing guidance among the sibling fare-discovery tools.

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 the meaning of origin, destination, departure_at, return_at, currency, direct and limit is already fully documented. The description adds only the round-trip pricing semantics, so the schema does the heavy lifting and baseline 3 applies.

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 and resource ('cheapest flights by route for a date or month') plus the sort order and price semantics, making it clear this is a round-trip/one-way fare search. It does not, however, differentiate itself from siblings like cheapest_destinations or price_calendar, so an agent must infer the boundary.

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 explains data freshness (48h cache, not live) which helps interpret results, but gives no when-to-use guidance and never names an alternative among search_places, cheapest_destinations, or price_calendar. Selection between these siblings is left entirely to inference.

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