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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context beyond that: no account/authentication is required, and the output is deterministic static sample data rather than live user data. It does not, however, say anything about output shape or size, though an output schema exists to cover that.

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?

Three short sentences with no filler, front-loading what the tool returns and then the usage condition. The fixed sample car is identified concretely, which is the single most decision-relevant fact.

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 need not explain return values. Combined with explicit usage conditions, the auth-free nature, and the deterministic sample behaviour, an agent has everything needed to call this 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 tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a parameterless tool applies. The description correctly communicates that no arguments are needed and none vary the result.

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 resource (the detailed report plus viewing advice for one named public sample car, CX52HHM) and its scope: it demonstrates what a detailed report contains rather than reporting on a real vehicle. This distinguishes it cleanly from siblings full_report and viewing_advice, which handle the user's own vehicle.

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?

Gives an explicit trigger ("Use when the user asks what RegTail's detailed report looks like") and an explicit exclusion ("It is always the same sample car, never the user's car"), which routes the agent away from this tool when the user wants their own car's data. No inference required.

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