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

Beyond the readOnly/idempotent annotations, it discloses genuinely useful behavior: individual partner names, phones and email are masked (with `data.mascarado: true`), company partners come whole, and responses are cacheable for up to 6 hours with a freshness caveat. That is exactly the kind of masking and caching context annotations cannot carry.

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 and useful, but the masking rule is stated twice – once as 'Sócio pessoa, telefones e e-mail vêm mascarados' and again in the following sentence – which is redundant text an agent does not need. Some tightening would raise this.

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 description does the heavy lifting by explaining the masking structure, the `data.mascarado` flag, and the 6-hour reuse window. It is close to complete for this tool, though it leaves the broader field list partly unspecified.

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 sole parameter's '14 dígitos' constraint is already in the schema, so the description adds no syntax or format detail beyond it. The baseline of 3 applies when the schema does the work.

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 ('Ficha de empresa por CNPJ') and pins the input format (14 dígitos). It clearly distinguishes itself from the sibling reveal_cnpj by contrasting masked vs. full data, so an agent can tell the two apart 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?

It names the alternative explicitly ('o completo é reveal_cnpj') and points to the endpoint that returns unmasked data, which gives clear context for choosing between them. It stops short of an explicit when-not-to-use statement for this tool, so it stays just under a 5.

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