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

Annotations already convey readOnly, idempotent, and non-destructive behavior, so the bar is lower. The description adds useful context about the comparison baselines (FIPE and active same-model listings). It does not disclose output format, units, or possible edge cases, but for a safe read-only tool this is acceptable.

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 description is two short sentences, front-loads the core purpose, and includes memorable example questions. There is no redundant or filler content; every phrase adds value.

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 single-parameter read-only tool with clear annotations, the description is largely sufficient for correct invocation. It explains what the tool compares and when to call it. The only minor gap is the absence of any indication about how the result is returned or interpreted (e.g., percentage, above/below FIPE).

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?

There is only one parameter, car_id, and the schema description coverage is 0%. The description indirectly explains the parameter by referring to 'DESTE anúncio', implying that car_id identifies the listing. It adds some context beyond the bare schema, but it does not explicitly define car_id or its format.

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 clearly identifies the tool's purpose: it returns the price position of a specific listing relative to the FIPE table and to active listings of the same model. The use-case phrasing ('esse preço é bom?') makes the intent concrete. It does not explicitly name sibling tools, but the focus on 'DESTE anúncio' versus market-wide tools provides implicit differentiation.

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 states when to use the tool: when the user asks whether a price is good, expensive, or cheap. It gives clear context and user-intent mapping. However, it does not mention when not to use it or point to alternatives among the sibling tools.

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