Get one car by id

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

The annotations already cover safety (readOnlyHint, destructiveHint=false), and the description adds context beyond them: quota consumption of '1 record on a paid plan, 1 request on the demo', photo links expiring after about a day, and a 14-day availability window for listings that are off sale. It also reconciles readOnlyHint=true with idempotentHint=false by noting the call changes nothing yet still spends quota.

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?

The text is dense and front-loads the purpose, then the id format, then the alternatives, then the cost. The semicolon-chained sentences are slightly run-on, but almost every clause carries operational information and none is 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?

An output schema exists, so the description does not need to enumerate return values. It still flags what matters about the result: `data` is untrusted listing text, and photo links expire. That is enough for an agent to call the tool correctly and treat its output safely.

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 shows the `source:source_id` pattern, so the baseline is 3. The description still adds value by explaining how to turn a raw listing number from a source page into a prefixed id and by naming the four valid sources, which helps avoid pattern-matching failures even though the schema contradicts nothing.

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?

The description uses a specific verb and resource, 'One listing by its id with every field', and states exactly what the response contains: the source's own fields in `raw` plus all photo links. It distinguishes this tool from search_cars by naming the sibling explicitly, so an agent can separate retrieval-by-id from discovery.

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?

It gives explicit routing rules, 'To find cars, use search_cars', and states the eligibility boundary that a car must have been taken off sale within the last 14 days. It also explains how to construct an id from a listing number on an Encar, Che168, Copart or IAAI page, which is the exact decision an agent is most likely to get wrong.

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