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

The annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is clear. The description adds value by detailing the two ways to identify the vehicle, the default for referencia, and the return object structure, which goes beyond the annotations.

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 concise, consisting of two sentences in Portuguese. It front-loads the purpose and efficiently covers identification methods, default behavior, and return format without wasted words.

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 the tool has 7 parameters, no output schema, and no enums, the description is fairly complete. It explains both identification methods, the optional referencia parameter, and the return object structure. However, it does not mention error cases or constraints like the format of codigo_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?

With 0% schema description coverage, the description compensates by explaining two identification methods: using codigo_fipe or a tuple of five parameters (tipo_veiculo, codigo_marca, codigo_modelo, ano_modelo, combustivel). It also clarifies that referencia is optional and defaults to the current month. However, it does not provide individual parameter types or constraints.

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 states 'Preço de referência FIPE de um veículo' (FIPE reference price of a vehicle), which uses a specific verb and resource. It clearly distinguishes from sibling tools like fipe_anos, fipe_historico, etc., by specifying that this tool retrieves the current reference price.

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 explains two identification methods and the default for referencia, but does not provide explicit guidance on when to use this tool versus alternatives (e.g., fipe_historico for historical prices) or when not to use it. The context is clear but lacks exclusions.

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