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

Annotations only cover readOnly/openWorld, but the description adds real behavioral context: per-IP and per-plan rate limits (3/day anonymous, 15/30/unlimited with keys) and the fallback behavior when mileage is omitted (uses median comparable mileage and flags it in `note`). That is meaningful disclosure beyond the structured hints, though it omits anything about comparison freshness or error cases.

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?

Front-loaded with the purpose followed by output description, quota rules, and mileage semantics. It is a bit dense and mixes English and French, but each sentence contributes usable information with no 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?

For a read-only estimation tool with no output schema, the description covers purpose, output fields, quota constraints, and the key mileage-omission behavior. It is largely self-sufficient; the main miss is any explicit routing versus the sibling search/stats tools.

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%, so baseline is 3, but the description adds genuine meaning beyond the schema: it explains that mileage is a second-order price factor, that omitting it triggers a median-mileage fallback reported via `note`, and it names the returned price tiers. This compensates well for what schema alone would carry.

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 (estimate) and resource (market price of a used car in France), and spells out the outputs (Q1/median/Q3, confidence index, comparable listings). It is unambiguous about what it returns, though it does not explicitly differentiate itself from siblings like car_market_stats or search_used_cars.

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?

Usage is implied rather than stated: it explains that mileage is optional and describes quota tiers, but never says when to pick this tool over search_used_cars or car_market_stats. Rate-limit context is present, but no explicit when-to-use/when-not guidance or named alternatives.

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