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

Annotations already declare this as a non-read-only, idempotent, non-destructive write. The description adds value beyond them: the saved trip becomes a PUBLIC page, the return includes a booking link on Kiwi.com, and prices are only confirmed on the booking site (i.e., prices here are not final). The public-page disclosure is a meaningful privacy signal absent from the annotations.

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 short sentences, front-loaded with the action and its inputs, then the return behavior and the pricing caveat. Every sentence carries distinct information; nothing is redundant with the title or annotations.

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 an output schema present, the description need not enumerate return fields, and annotations cover the safety profile; the remaining behavioral notes (public page, booking link, price confirmation) are the ones an agent actually needs. It could say a bit more about the durability of the saved trip, but nothing essential 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 description coverage is 100%, so the single parameter is already fully documented in the schema (source tools, any order, 1–8 items). The description only restates the source of the ids, adding no new syntax or constraint, 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?

Specific verb+resource ('Save a trip from flight ids') plus the outcome ('returns a public page with the trip and a booking link'). It also names the sibling tools that produce the required input (search_flights, plan_trips), so an agent can place it correctly in the workflow 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?

Clearly implies the precondition: flight_ids must come from search_flights or plan_trips, so the agent knows this is a downstream step, not a standalone lookup. It gives no explicit when-not guidance (e.g., whether repeated saves create duplicates), which keeps it just short of a 5.

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