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

Annotations already declare readOnly/non-destructive/openWorld, but the description adds substantial behavioral detail: the service fee is reported separately because Omio treats it as non-refundable, and it explains what the call returns for fares that can't be cancelled online. It also states the API-key/access prerequisite.

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?

Front-loads the core purpose well, but the 'why the fare cannot be cancelled online' idea is stated in the first sentence and repeated in the third, and the refund/service-fee point is restated. Efficient overall but with minor redundancy.

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?

No output schema exists, so the description carries the return-value burden and does so: it explains the refund, the separated service fee, and the reason-string case, plus the auth requirement. An agent has everything needed to invoke and interpret the call.

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% and there is only one parameter (booking_id, documented as coming from list_bookings). The description adds no additional syntax or format guidance beyond the schema, 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 (get a cancellation/refund quote) with the scope split into two outcomes: refund amount or a reason cancellation is not possible online. The closing 'Nothing is cancelled' pins it apart from the sibling omio_cancel_booking without ambiguity.

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 clear context: call this before cancelling, and online cancellation only applies to a refundable fare or an Omio Flex booking. It doesn't explicitly name omio_cancel_booking as the follow-up action, but the 'before you cancel' framing and 'Nothing is cancelled' strongly imply the usage boundary.

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