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

Annotations already establish readOnly, idempotent, non-destructive and closed-world behavior, so the bar is lower. The description still adds real signal: the data is "public" (no user scoping or auth context) and "full" (not a summary/preview), plus it enumerates exactly which facets come back — useful since there is no output schema.

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?

Two sentences, no filler, with the return content front-loaded and the parameter instruction second. Every clause earns its place.

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 one-parameter read with no output schema, the field enumeration is the key compensating detail and it is present. Missing only edge-case behavior (invalid id, listing removed/expired) and whether photo/room sub-structures are truncated.

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% and the schema already documents the single parameter as a UUID or a room-ly.org/listing/... url. The description only restates that and adds provenance ("from search_listings"); it contributes no format or validation detail beyond structured data, so 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?

"Full public details of one Roomly listing" states a specific verb and resource, then enumerates the payload (price, dates, description, rooms, inclusions, amenities, photos). That is enough for an agent to distinguish it from search_listings without opening the 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?

"Pass the id or the url from search_listings" tells the agent this is the follow-up fetch step after a search, i.e. it names the prerequisite source of the identifier. It does not state exclusions or what to do if the listing is not found, so it stops short of full when/when-not guidance.

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