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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description still adds useful behavior beyond them: deterministic ordering (soonest first), the selection criterion (departure date, not price/discount), and the explicit absence of date/destination filters. Deduction: it references a 'windowDays' input that does not exist in the schema, which is stale/incorrect behavioral detail.

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?

Front-loaded with the core behavior (what it returns and ordering) before caveats, and no sentence is pure filler. The keyword enumeration ('last minute, near-term, urgent, right away...') is somewhat padded, but it plausibly serves query-intent matching.

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 an output schema present, return values need no explanation, and annotations carry the safety profile. The description supplies everything else an agent needs: scope, sort order, selection basis, and the lack of date/destination filters.

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 limit, currency, and language are already fully documented and the baseline is 3. The description adds nothing about those parameters, and its only parameter-related sentence refers to a nonexistent 'windowDays', which is mildly misleading rather than additive.

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 (returns tours) plus a precise scope: departures soon, sorted soonest first, selected by departure date only. It also disambiguates from a discount-style listing ('it is not a discount') and from filtered searches ('no date range or destination filter'), so an agent can distinguish it from search_tours/search without opening schemas.

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 intent list (last minute, near-term, urgent, right away, this week, airfare-price) tells the agent exactly which user phrasings should route here, and the 'not a discount' and 'no date range or destination filter' clauses set expectations for when NOT to use it. However, it never names a sibling tool as the alternative for filtered searches, leaving that routing to inference.

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