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

Annotations already declare readOnlyHint=true, so safety is covered; the description adds that the full record is large and that fields narrows the response, plus discloses the POST /v1/rex/Listings/read endpoint. No mention of permissions or error behavior, but little more is needed for a read tool.

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 compact sentences, front-loaded with the resource and payload, followed by id provenance and the endpoint. No filler.

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 no output schema, the description usefully enumerates the returned sections. It does not describe pagination or size mitigations beyond the fields hint, but for a single-record read it is nearly complete.

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 fields parameter is already documented in-schema including the 'omit for whole record' caveat. The description only adds provenance for the id, which is useful but slight; 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?

States a specific verb+resource ('One listing by id') and enumerates the payload (state, price, agents, property attributes, images, contacts, events). It is clearly distinguishable from the search/autocomplete siblings.

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 id comes from a search or autocomplete' implicitly points the agent at rex_search_listings / rex_autocomplete_listings as the prerequisite step. There is no explicit 'do not use for lookup by name' exclusion, but the context is clear.

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