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

With no annotations provided, the description carries the full burden and does well: it discloses exactly what content comes back, including direct booking links to the host's own site and 'exact location.' It does not address auth requirements, error/failure behavior for invalid identifiers, or rate limits, which keeps it below 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?

Three sentences, front-loaded with the returned payload and then the usage trigger, with no filler. The enumeration of returned fields is long but each item is informative rather than redundant.

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?

There is no output schema, so the description must describe the return value, and it does so comprehensively. Combined with the accepted identifier formats, an agent has enough to invoke correctly; only failure-mode and auth context are 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% so the baseline is 3, but the description genuinely adds meaning: the single id parameter accepts a uuid, a URL slug, or a short code ('1zwf' in cielstay.com/l/1zwf), which is broader than the schema's narrower note ('listing ID from a previous search result'), helping an agent pass user-supplied URLs directly.

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?

Specific verb (fetch) plus a precisely scoped resource (complete details for a specific CielStay listing) with an enumerated payload: description, photos, amenities, house rules, location, and booking links. It is immediately distinguishable from sibling search/discovery tools like search_vacation_rentals and refine_search.

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?

Explicit trigger conditions are given: 'when the user wants to learn more about a specific property' or 'wants to know whether it can be booked directly with its owner.' No alternatives or when-not conditions are named (e.g. use search_vacation_rentals first to obtain the id), so it falls short of the fully routing-oriented top score.

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