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

With no annotations, the description carries the behavioral burden and does so well: it discloses return fields, that the PDF is not delivered via MCP, exact cost tiers, that errors are not charged, and that certain negative responses count as a query. Only auth/permission details are absent, which are likely handled by the MCP layer.

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 purpose, then returns, PDF caveat, cost, and billing rules. The cost tier list is verbose but necessary for the confirmation step, and the structure remains logical and efficient overall.

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 an output schema and full schema coverage, the description is nearly complete for this moderately complex tool. It omits an explicit statement that confirmo_custo=true is required to execute, but that detail is fully covered by the schema.

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 coverage is 100%, so all three parameters are fully documented in the schema. The description reinforces the 'one document only' constraint and gives cost details relevant to confirmo_custo, but adds no meaningful semantics beyond what the schema already provides.

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 a specific verb ('Consulta') and resource ('Certificado de Regularidade do FGTS (Caixa)') with scope 'CPF ou CNPJ (um só)'. This is clearly distinguishable from sibling tools like consultar_cnd_federal or consultar_cndt because the FGTS certificate is a unique document type.

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 implies usage by naming the certificate and input constraint, and provides cost context. However, it does not explicitly say when to choose this tool over similar certificate consultas (e.g., CND estadual/federal) or state any preconditions beyond cost, leaving routing guidance to be inferred.

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