Consultar CNPJ (básico)

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

Annotations already declare read-only, idempotent, non-destructive and open-world, so safety is covered. The description adds genuinely non-obvious behavior: a free daily quota per connection versus a 1-credit cost when BITBUSCA_API_KEY is supplied, and a precise inventory of what data is and is not returned. It does not say what happens when the quota is exhausted, which keeps it below 5.

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?

Two dense sentences with zero filler: the first front-loads what data comes back and what does not, the second front-loads the cost model. Nothing is repeated from the schema or annotations.

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 single-parameter lookup with no output schema, the description fully compensates by listing the returned fields, the exclusions, and the pricing/quota behavior. An agent has everything needed to decide whether to call it and what to expect back.

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?

With one parameter at 100% schema description coverage ('CNPJ com ou sem pontuação, aceita o alfanumérico'), the schema already carries the semantics. The description adds no extra format, normalization, or validation detail beyond that, so the baseline 3 applies.

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?

States a specific verb+resource (consulta do cadastro público do CNPJ na Receita Federal) and enumerates exactly which fields come back: razão social, nome fantasia, situação, abertura, natureza jurídica, porte, CNAE principal, endereço, Simples/MEI. The explicit exclusions ('Sem sócios e sem contatos') plus the '(básico)' framing let an agent distinguish this from richer company tools like buscar_empresas without opening either schema.

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 'Sem sócios e sem contatos' clause effectively tells the agent when NOT to use this tool, and the key/quota clause explains the two operating modes. It stops short of naming the alternative sibling to use when partner or contact data is needed, so routing is implied rather than explicit.

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