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

Adds substantial context beyond the readOnly/openWorld annotations: the empty-state behavior before check-in, the alternate check-in path that yields no Kiwi.com pass, the one-link-per-passenger-per-flight return shape, and the required Cotlet API key authorization. These are exactly the behavioral traits an agent needs and the annotations do not supply.

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 key information (what is returned, when) is front-loaded and every sentence carries meaning, but the opening 'Boarding passes Kiwi.com received after checking you in' is a fragment and the check-in condition is restated twice, adding mild 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?

For a simple single-parameter read with no output schema, the description covers output format, empty state, source conditionality, and auth requirements. An agent has everything needed to decide whether to call it and what to expect back.

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% with a single documented parameter (trip_id = booking number from list_trips), so the schema already carries parameter semantics. The description adds no parameter detail (it never mentions trip_id), 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 and resource: retrieve boarding passes Kiwi.com received after check-in, returned as download links. It clarifies the cardinality (one link per passenger and flight) and distinguishes the state from the check_in flow, so an agent can tell it apart from siblings like get_trip or check_in without opening a 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?

Explains the condition under which the tool is useful: results appear only after Kiwi.com checks you in, otherwise the list is empty and check_in reports what is pending. It also rules out the self-check-in case ('the airline sent the pass and Kiwi.com has none'). Clear context and an implied exclusion, though the imperative 'call this after check-in' is left to inference.

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