validate_cnpj

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

No annotations provided, so description must carry full burden. It discloses the algorithm (mod-11 check digits) and that it replaces blind trust in digits. However, it does not mention return format or side effects (e.g., read-only). Adequate but not comprehensive.

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 sentences, front-loaded with action and algorithm, followed by usage context. No wasted words; concise and efficient.

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 validation tool with no output schema or annotations, the description covers purpose, method, and context. It could specify the return type (boolean or validation result) but is otherwise complete.

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 100% with clear description of the single parameter (cnpj as 14 digits, punctuation ignored). The tool description adds no extra meaning beyond what the schema already provides.

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 it verifies a Brazilian CNPJ using mod-11 check digits. It distinguishes from 'trusting 14 digits' but does not differentiate from sibling validate_cpf (also Brazilian). The verb 'verify' and resource 'CNPJ' are specific.

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?

Explicitly says 'Call this for onboarding Brazilian businesses', providing a clear use case. While it doesn't specify when not to use, the sibling context of other validate_* tools implies alternatives for different identifiers.

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