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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds an important behavioral requirement: CPF queries need birthdate. No contradictions with annotations are present.

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 concise sentences, front-loaded with the core purpose and followed by a key conditional requirement. There is no redundant or filler content.

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 read-only query tool with good annotations, the description covers the essential context: target certificate type, accepted identifiers, and the CPF/birthdate condition. It does not describe return format or error cases, but the term 'Certidão' and the absence of an output schema make the primary return value reasonably clear.

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 coverage is 0%, so the description must compensate for the bare input schema. It adds meaning by indicating 'por CNPJ ou CPF' and that CPF requires birthdate. However, it does not specify formats for CPF, CNPJ, or birthdate, nor whether exactly one identifier is mandatory.

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 identifies the tool's purpose: returning a federal tax clearance certificate (CND Federal/PGFN) by CNPJ or CPF. The qualifier 'Federal/PGFN' helps distinguish it from sibling tools like consultas_cnd_estadual, though it lacks an explicit verb such as 'consultar' or 'obter'.

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 provides useful context by stating that CPF queries also require birthdate, which is a prerequisite for use. However, it does not explicitly state when to choose this tool over alternatives like consultas_cnd_estadual or consultas_cndt; the differentiation is only implied through 'Federal/PGFN'.

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