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

The annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds behavioral value by enumerating what the returned record includes—full description, features, photos, seller, and original source URL to cite—which helps the agent know what to expect beyond the output schema.

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 with no filler; the first sentence states the core action and scope, and the second provides usage context and return-value expectations. Every clause earns its place, and the most important information is front-loaded.

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?

Given a single well-documented required parameter, an output schema, and annotations covering safety and idempotency, the description supplies the remaining contextual need: when to invoke it and what the result is used for. Nothing critical is missing for an agent to select and call the tool correctly.

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?

The input schema already provides 100% coverage for the only parameter, slug, describing it as the unique listing slug returned by search_cars. The description merely repeats 'by its slug' without adding new semantic detail, so the schema carries the full burden and the baseline of 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?

The description starts with a specific verb and resource: 'Get the complete record of one used-car listing in Portugal by its slug.' It clearly names the listing scope and the identification mechanism, and it differentiates from sibling search tools by focusing on a single record's full detail rather than a list.

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 description explicitly says 'Use this after search_cars when the user asks about a specific car,' providing a clear trigger condition and preceding-step context. It does not explicitly enumerate when-not-to-use or name alternatives like find_similar_cars or get_price_stats, but the context is unambiguous enough to guide correct selection.

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