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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavior beyond that: unpublished tours fail with PRODUCT_NOT_FOUND, absent data is surfaced in a `missing` field rather than omitted silently, and pricing is deliberately limited to the first departure — all useful for interpreting results.

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 purpose and then a compact inventory of returned fields, with the edge cases (missing, PRODUCT_NOT_FOUND, first-departure-only pricing) at the end. It is dense but every clause carries information; a bulleted list of fields would read slightly better than the run-on sentence.

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?

An output schema exists, so the field inventory is somewhat redundant, but the description still covers the things the schema does not: the unpublished-tour error code, the `missing` fallback for empty fields, and the pricing scope. Nothing an agent needs to call it correctly appears to be absent.

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 clear descriptions for slug (product.slug), currency and language, and both enums are spelled out. The description adds essentially nothing about parameter meaning beyond the fact that currency drives the quoted price, 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?

Opens with a specific verb+resource ('Returns one tour') and enumerates exactly what the record contains: description, airline, nights, itinerary, inclusions, hotels, upcoming departures and first-departure pricing. The closing line 'Only the first departure is priced here' cleanly separates it from get_departures, so an agent can pick between the two without opening either 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?

Usage is only implied: the note that only the first departure is priced here hints that get_departures is the tool for full pricing, and PRODUCT_NOT_FOUND explains an unpublished-slug outcome. There is no explicit 'use this when…' statement or named alternative, so the agent must infer the routing.

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