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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful non-annotation context: the result is a set of sellers (airline direct and agencies) each with price and an external checkout link, which sets expectations for an open-world read. It does not add auth, rate-limit, or freshness/caching details, so it falls short of a 5.

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: purpose first, then the prerequisite constraint, then the exclusions. Every clause carries routing or prerequisite information, and nothing is repeated from the schema beyond necessary framing.

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?

Annotations cover the safety profile, the output schema covers return values, and the single parameter is fully documented in the schema. Combined with the description's explicit prerequisites and alternatives, an agent has everything needed to invoke this 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?

With 1 parameter at 100% schema description coverage, the schema already documents itinerary_id, and the description largely restates it (one-way from search_flights, round trip from search_return_flights). The only added nuance is the word 'complete', which is already implied by the schema wording, so the 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+resource: retrieving the sellers offering a chosen itinerary, with each seller's price and checkout link. It explicitly names the sibling tools it derives from (search_flights, search_return_flights) and the one it is not (track_flight), so an agent can distinguish it without opening any schema.

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 an explicit trigger ('when the traveler wants to book flights they have chosen'), an explicit exclusion ('not for an outbound alone – choose a return first'), and an alternative for a different intent ('not a price watch (track_flight)'). The when/when-not/alternative triad is fully covered.

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