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

Annotations already cover the safety profile (readOnly, non-destructive, openWorld), yet the description adds substantial context beyond them: whole-itinerary scoping of the sold options, the precise empty-result conditions (36h cutoff, self-transfer short layovers), and the explicit auth requirement ('Needs the user's Cotlet API key with access to this app'). This is genuinely useful behavioral disclosure.

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 summary sentence is front-loaded and the following sentences layer in scoping, empty conditions, and auth. There is mild redundancy between 'with the price of each' and 'each with its price,' but the overall length is justified by the number of distinct facts conveyed.

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 carries the burden of explaining returns (bag options, each with price and associated passenger), scoping, the empty-result cases, and the auth requirement. Nothing an agent needs to call and interpret this tool 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% and there is a single parameter (trip_id), which the schema already documents as 'Booking number from list_trips.' The description adds no input-side meaning beyond the schema, so baseline 3 applies. The mention of 'the passenger it is for' pertains to output, not input.

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?

The description states a specific resource and scope: 'Bags you can still add to a trip, with the price of each' and 'Returns the bag options Kiwi.com offers for the itinerary.' An agent can immediately tell this is a read/list operation distinct from the write-oriented sibling kiwi-com_add_baggage.

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?

It gives clear operational context: options are sold for the whole itinerary, and the list is empty from 36 hours before departure and for self-transfer itineraries with short layovers. This tells the agent when results will be empty, though it never explicitly names an alternative tool or states 'use this before calling add_baggage,' so it stops short of a full when/when-not/alternatives statement.

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