Get car details

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

Annotations already cover read-only/idempotent/no-destroy, and the description goes well beyond them: it discloses what is deliberately withheld (seller contacts, reserves), that missing facts may be null, the isError=true + structuredContent.error failure contract, and that the call has no side effects on a seller or reservation. That is rich behavioral context an agent cannot get from the annotations.

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?

Dense but front-loaded: purpose first, then input sourcing, then alternatives, then return shape, then null/error semantics, closing with a side-effect disclaimer. Each sentence carries distinct information despite the length.

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 a single parameter, no output schema, and no nested objects, the description supplies everything needed: return payload contents (specs, BDT price, currency, description, up to eight images, listing URL, optional inspection summary and auction_id), the auction_id handoff to get_auction_status, and null/error handling.

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 property already spells out the ID/slug format and the "not the URL, VIN or registration number" rule. The description restates essentially the same constraint plus its provenance (search_vehicles / public URL), adding minimal value beyond structured data; 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?

Opens with a specific verb+resource+scope: "Retrieve full public detail for one JOY Auto Exchange listing." It explicitly positions itself against search_vehicles and compare_vehicles, so an agent can route without inspecting schemas.

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?

States exactly what input to supply (listing_id from search_vehicles or a slug from a listing URL), warns to pass only the ID/slug rather than the full URL, and names both alternatives with the conditions that select them (search_vehicles for discovery, compare_vehicles for 2-4 cars). Effectively no inference required.

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