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

No annotations are provided, so the description carries the full burden. It does add genuinely useful behavioral context that isn't in structured fields: a cost signal ('Price: $0.01') and a privacy disclosure that partner personal names are excluded. It says nothing about failure behavior for invalid CNPJs or about result caching/completeness, so the disclosure is partial.

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?

One dense sentence that front-loads the resource and CNPJ key, then lists returned fields before the trailing price note. No filler and nothing redundant.

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?

With no output schema, the field enumeration substitutes well for a return-value description, and the single parameter is fully covered by the schema. Only error/edge behavior for malformed CNPJs is left unaddressed, a minor gap for a single-param read tool.

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 100% and the single cnpj parameter is already documented with formatting and alphanumeric rules, so the baseline applies. The description only restates 'by CNPJ' and adds no format or validation detail beyond the schema.

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 ('Brazilian company registration data by CNPJ') and enumerates the returned fields (legal name, status, address, partners, CNAE, capital), so the agent knows exactly what this returns. It does not explicitly contrast with close siblings like get_company_dossier, get_company_kyb, or get_company_score, which is the only thing keeping it from a 5.

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?

There is no when-to-use / when-not-to-use guidance and no mention of the several overlapping siblings (get_company_dossier, get_company_kyb, get_company_score, batch_company_score). The agent must infer from the name alone whether this is the right lookup versus a dossier or scoring tool.

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