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

Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real behavior: it discloses the next_actions payload the caller gets back, the live trust-score badge, the 404 not_found failure mode, and that no payment or account is needed. It doesn't cover pagination or auth, but for a single-record read that is minor.

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 action in the first clause, then progressive detail on returned fields and error behavior. Dense but every clause carries information; the embedded REST-endpoint reference and next_actions explanation are the slight heavy spots.

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 carries the burden of explaining returns, and it does describe next_actions and the trust-score badge plus the 404 error path. It is close to complete for a one-parameter read tool; only return shape details (full field list) are left unspecified.

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% and the single parameter (UUID listing_id) is fully documented in the schema, including where to source it. The description adds only 'by id', so the baseline 3 is appropriate.

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 ('Fetch one listing by id') and pins it to the equivalent REST endpoint GET /listings/{id}, so the agent knows exactly what it retrieves. It does not name the close sibling alternatives (search_listings, describe_listing) to differentiate, capping it below 5.

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 implied by the 'by id' framing and the schema's note that ids come from search_listings, but the description never states when to use this instead of search_listings or describe_listing, nor any preconditions beyond an id being available. It adds the useful 'free, no payment or account required' constraint but no routing guidance.

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