validar_cnpj

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

With no annotations provided, the description carries the full burden of disclosing behavior. It adds useful context by stating that both numeric and alphanumeric formats are accepted and that the format is auto-detected. However, it does not mention what the function returns (e.g., true/false) or behavior on invalid input, so transparency is partial but not absent.

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?

The description is two sentences, front-loaded with the core purpose, and every sentence adds value: the first states the function, the second covers format compatibility and auto-detection. No wasted words.

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 simple one-parameter validation tool with no output schema, the description covers the essential context: what it does and the input formats. It does not explicitly state the return value, but that is implied for a validator. The description is sufficiently complete given the low complexity.

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 0%, so the description must compensate. It does add meaning by explaining that the 'cnpj' parameter can be in numeric or alphanumeric format and that detection is automatic. Yet it omits specifics like length, punctuation handling, or examples, leaving some ambiguity about the exact accepted input format.

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's function: 'Valida se um CNPJ é válido' (validates if a CNPJ is valid). It uses a specific verb (valida) and resource (CNPJ), and the sibling tools include validar_cpf and gerar_cnpj, which are clearly differentiated by document type and operation (validate vs. generate).

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 purpose is so specific that the usage context is clear—use this tool to validate a CNPJ, as opposed to generating one (gerar_cnpj) or validating a CPF (validar_cpf). However, it does not explicitly state when not to use it or directly name alternatives, so it falls 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.