validate_cnpj

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 discloses the return object with `valid` and `reason` for invalid cases, and the accepted input formats. It does not detail edge-case behavior, but for a pure validation function this is adequate.

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 short sentences, front-loaded with the verb and resource. No unnecessary detail.

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?

The tool is simple with one parameter and no output schema. The description adequately explains its purpose, input format, and return value, making it complete for an agent to select and invoke 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?

The input schema already covers the `cnpj` parameter with a description of 'formatado ou apenas dígitos'. The description adds a concrete example ('11.222.333/0001-81') which reinforces the accepted format, but does not add substantial new semantics 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?

The description clearly states the tool validates a Brazilian CNPJ, specifying accepted input formats (formatted or raw digits) and the return structure. This distinguishes it from sibling tools like validate_cpf (CPF validation) and generate_cnpj (CNPJ generation).

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 for CNPJ validation, which is clear from the purpose. It does not explicitly mention alternatives or when not to use, but the sibling tool names provide context. Effective for a straightforward validation tool.

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