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

With no annotations, the description carries the full burden and does so: it reveals the credit cost per plan tier, that errors are not charged, that "sem inscrição encontrada", "sem_certidao" and "nao_contribuinte" responses still consume a consultation, that the PDF is not delivered via MCP, and that confirmation is mandatory before execution.

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?

Front-loaded with purpose and output summary, then cost and billing edge cases. The per-plan price list is long but justified because the agent must relay cost before the user can confirm; the parenthetical recharge prices add minor bulk.

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?

An output schema exists, yet the description still summarizes returned fields (status, emissão, validade, protocolo) and flags the PDF limitation. Cost, billing exceptions, and the two-step confirmation flow are all covered, leaving nothing an agent needs to call it correctly.

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 already documented, and the description reinforces the single-document constraint. It adds real meaning for confirmo_custo by tying it to the cost figures, explaining that without it the tool only explains pricing and performs no lookup.

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?

Names a specific verb ("Consulta") and a precisely identified resource ("Certidão Negativa de Débitos Trabalhistas (TST)"), scoped to "um CPF ou CNPJ (um só)". The certificate type itself separates it from siblings such as consultar_cnd_federal, consultar_cnd_estadual and consultar_crf_fgts without needing to name them.

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?

Makes the usage precondition explicit: the call only executes after the user accepts the stated cost, and otherwise the tool just explains pricing. It does not name the alternative certificate tools or state when to pick CNDT over federal/estadual, which keeps it short of a 5.

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