validar_cpf

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

Without annotations, description carries the burden. It discloses the offline/mathematical nature, absence of external API calls, and that it only validates the check digit, not existence. This is transparent enough.

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 sentence with purpose, one with transparency. No fluff. Well-structured.

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?

Given a simple single-parameter tool and an output schema present (per context), the description is complete. It clarifies the scope (check digit only) which is important contextual information.

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 schema already fully describes the 'cpf' parameter with examples. The description adds no additional parameter semantics beyond that, so baseline 3.

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 'Valida' and the resource 'dígito verificador de um CPF brasileiro'. Clear and distinguishes from siblings like consultar_cnpj.

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?

Gives context that it is offline and does not query external APIs, and notes Receita Federal's lack of public API for CPF data. However, it doesn't explicitly contrast with sibling tools or provide when-not-to-use scenarios.

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