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

Annotations already declare readOnlyHint=true and idempotentHint=true. The description adds context about public data access, LGPD responsibility, and the payment model (prepaid credit). These go beyond the annotations and help the agent understand the tool's non-technical constraints and data sensitivity.

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 (three sentences) and front-loaded with the primary purpose. Every sentence adds meaningful information: purpose, access/payment method, and data classification. No filler or repetition.

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?

The tool has no output schema, and the description does not mention expected return values. Combined with the unclear parameter requirements (both CPF and CNPJ required, unexplained 'completo'), the agent lacks complete information. However, the core operation is simple, and the annotations cover safety aspects, making this adequate but clearly incomplete.

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 mentions 'CPF ou CNPJ' but the schema requires both Cpf and Cnpj, creating ambiguity about which input(s) to provide. The optional 'completo' parameter is not explained at all. Without details on formats or semantics, the agent is likely to misuse the parameters.

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 states the tool's purpose with a specific verb and resource: 'Verifica se uma pessoa ou empresa consta na Lista de Devedores da União (PGFN) a partir do CPF ou CNPJ.' This exactly defines the tool's function and differentiates it from unrelated sibling tools like authenticate or show_version.

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 useful usage context: 'Hospedado pela plataforma, sem credenciais, pague por consulta com crédito pré-pago' explains operational prerequisites. It implies when to use this tool (for checking debtors) but does not explicitly mention when not to use or name alternative tools. Since siblings are generic, this clarity is sufficient.

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