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

With readOnlyHint, openWorldHint, and destructiveHint already declared, the description usefully adds that date flexibility caps at 3 days and that results carry booking links (a side-effect-relevant detail). It also discloses the auth requirement (Cotlet API key with app access), which the annotations do not cover. Missing rate-limit or result-count behavior keeps it from a 5.

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 opening is well front-loaded, but the middle is redundant: "a booking link" in sentence one is restated as "each with a link to book on Kiwi.com" in sentence two, and "the flights Kiwi.com finds" repeats "Searches Kiwi.com flights." Tighter editing would remove roughly a sentence of overlap.

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 read-only search with no output schema, the description covers the key facts an agent needs: inputs (two places, dates, one-way vs round trip), the flexibility cap, and what the results contain. It is close to complete, with only result volume/pagination left unstated.

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 the schema already documents all 7 parameters. The description only reinforces the flex_days range ("up to 3 days either side"), which the schema also states, adding essentially no new meaning. Baseline 3 is correct when the schema does the heavy lifting.

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 (searches) plus resource (Kiwi.com flights) and scope (one-way or round trips, two places, set dates). It also names the return contents (price, duration, booking link), so the agent knows exactly what the call produces. This distinguishes it from the sibling kiwi-com trip, baggage, and seat tools, which operate on already-booked trips.

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 does not need your trips, so it works before you book anything" gives clear context on when to reach for this tool versus the trip-management siblings. It doesn't explicitly name an alternative search tool, but none exists among the siblings, so the guidance is adequate without it.

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