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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the required Cotlet API key with access to this app, and the fact that fare conditions (exchangeable/refundable) drive change/cancel decisions. Return format is described rather than left implicit.

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?

The first sentence lists the fields ('Journey, passengers, fare conditions, Omio Flex, confirmation status and price paid') and the second sentence repeats the same list with slightly more detail, which is redundant. The one new piece of information (the API key requirement) is buried at the end.

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 no output schema, the description does the right thing by enumerating return values, and it discloses the auth prerequisite. For a single-parameter read tool, this is largely sufficient, though the change/cancel routing could be spelled out more concretely.

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 the single parameter booking_id is documented in the schema as 'Booking ID from list_bookings.' Baseline 3 applies; the description adds no syntax or format detail beyond what the schema already provides.

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 clear verb+resource ('Returns one booking') and enumerates the returned fields, so an agent knows exactly what it retrieves. It does not differentiate itself from the sibling omio_get_trip, which also returns journey information, leaving some ambiguity about which to pick.

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 line 'Your agent reads the conditions to know whether it can still change or cancel the trip' implies a use case (checking before change/cancel), but it never names omio_change_booking, omio_cancel_booking, or omio_get_cancellation_quote as the alternatives. Usage context is implied rather than explicit.

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