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

Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds meaningful beyond-annotation context: the cost model, lack of credentials, public/official data source, and LGPD obligations for the controller. This is exemplary transparency.

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 front-loaded with the core purpose and data fields, followed by essential pricing and legal context. Each sentence earns its place; the legal/LGPD sentence adds important compliance guidance without being verbose.

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 relatively simple query tool with strong annotations, the description covers the purpose, returned data categories, access/cost model, data source status, and legal responsibility. Without an output schema, its enumeration of fields provides adequate completeness. A minor gap is the lack of any pagination or response format detail, but that is not material here.

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 description coverage is 0%, so the description must compensate. It clearly indicates that 'Placa' is the lookup key and describes the response fields, but it does not explain the 'completo' boolean parameter or expected input formats. Partial compensation for an otherwise obvious parameter.

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 uses a specific verb ('consultar') and resource ('veículo a partir da placa'), lists concrete data fields (marca, modelo, ano, cor), and clearly distinguishes this from sibling tools like authenticate or report_bug, which serve entirely different purposes.

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?

It clearly states the access model (no credentials, pay-per-query with prepaid credit) and the data's public nature, giving the agent enough context to decide when to invoke it. It does not explicitly mention when not to use it or name alternatives, but sibling tools are unrelated, so the context is sufficient.

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