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

The description adds significant context beyond annotations: it's a paid service with prepaid credit, requires external login credentials (distinguishing from platform credentials), and clarifies that the data is non-confidential citizen-accessible info. It also addresses LGPD data control responsibility. This exceeds the simple readOnlyHint=true annotation, though it doesn't describe error rates or response specifics.

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 (4 sentences) and front-loads the purpose in the first sentence. However, three sentences are dedicated to business/legal caveats (payment, LGPD) rather than technical usage, which is less critical for invocation. It is not bloated, but the content balance is skewed.

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 8 parameters, no output schema, and no parameter explanations, the description is insufficient for someone to invoke the tool correctly. It covers the legal/commercial context but omits essential details about input requirements and expected response format, leaving a significant usability gap.

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 schema has 8 string parameters with zero description coverage. The description explains none of the parameters, including required fields like a3, a3_pin, login_cpf, and login_senha. Even optional identifiers (placa, chassi, renavam) are not mapped to the query, leaving the agent unable to construct a valid request.

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 the tool performs a query ('consulta') against official Brazilian sources for vehicle BIN/RENAVAM data. It clearly differentiates from the generic sibling tools (e.g., authenticate, connect). The term 'Cadastro' adds slight ambiguity, and it doesn't explicitly list the returned data, but the core purpose is clear.

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 provides pricing and legal context (prepaid credit, LGPD) but gives no explicit instructions on when to use this tool over alternatives or any exclusions. Sibling tools are generic, so no differentiation is made, leaving the agent to infer usage from the purpose alone.

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