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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description usefully enumerates the returned data domains, but adds nothing on auth, rate limits, or freshness beyond what the schema and annotations already convey.

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, zero waste, with the resource scope front-loaded and the ID-provenance hint trailing. 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 single-record detail tool with an output schema, the description covers the required input and its source and previews the payload. Nothing critical for correct invocation is missing, though it could note it operates on one listing at a time relative to batch/search siblings.

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 listing_id as a UUID path segment of a /vehicledetail/ URL. The description repeats the UUID type and the name but adds no new syntax or format detail, 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?

States a specific verb (Fetch) and resource (one Cars.com listing) and enumerates the payload contents: specifications, deal-fairness score, features, AutoCheck history, price changes, seller notes, seller details. It is clearly distinguishable from the sibling carsdotcom_search, which it explicitly points back to.

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?

Explicitly tells the agent where to obtain the required identifier ("Get the ID from carsdotcom_search"), establishing the search-then-fetch workflow. It stops short of stating when not to use it or naming other alternatives, so it lands at 4 rather than 5.

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