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

Goes well beyond annotations with material behavior: total includes the service fee, bank approval returns a link the agent must not bypass, per-call confirmation is on by default and switchable, and it requires a Cotlet API key with app access. Annotations only cover read/write and openness; this adds the auth, confirmation, and payment-completion traits an agent needs.

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?

Content is front-loaded with the booking action, but it repeats the service-fee point twice ('confirm the total, including the service fee' then 'The total includes Omio's service fee') and the flow is somewhat meandering across confirmation, bank approval, and auth notes.

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 mutation tool with no output schema, the description covers the safety-relevant essentials: what is charged, when it is charged, the bank-approval link path, the confirmation default, the reach-other-people caution, and the required API key. Nothing an agent needs before calling 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 fare_id/trip_id/passengers/add_omio_flex/seat_preference are already documented in the schema. The description reinforces the get_trip provenance of fare_id but adds no syntax or format detail beyond structured data, matching the baseline for full coverage.

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 ('Book a fare on your account') and scopes the source ('the fare you pick from get_trip'), so it reads clearly as the checkout step. It does not name a sibling explicitly (e.g., omio_change_booking/cancel), so differentiation is implied rather than stated.

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?

Clear context: it is the post-selection booking step for a fare obtained from get_trip, with the total confirmed before payment. No explicit exclusions or named alternatives for change/cancel scenarios, so it stops short of full when-not guidance.

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