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

Annotations are sparse (readOnlyHint false, destructiveHint false, etc.). The description adds meaningful behavioral context: it confirms the tool performs local validation and decoding, and explicitly denies RENAPO registration confirmation, which is a side-effect disclosure. It also notes the package billing context ('Incluido con saldo de paquete'), which is a usage condition. No contradiction with annotations.

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 three concise sentences. The primary purpose is front-loaded in the first sentence, the package inclusion is a short secondary note, and the limitation is stated last. Every sentence earns its place with zero filler.

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 has one parameter and an output schema (not shown). The description covers what it does, what it returns (decoded info implied), and the crucial limitation about RENAPO. It also mentions the package billing condition. For a simple validation tool, this is adequately complete; missing explicit error handling is acceptable given the output schema.

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 carry the parameter meaning. It clearly identifies the parameter as a CURP to validate, and the description of validation (formato, digito verificador, decodificacion) adds semantics beyond the schema's bare 'string' type. It does not explicitly state the expected format, but the purpose is evident.

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 uses a specific verb 'Valida' and a specific resource 'CURP', and clearly enumerates the scope: formato, digito verificador, and decodificacion. It also explicitly states what it does not do ('No confirma registro ante RENAPO'), which further differentiates it from any sibling that might check official registry. This is unambiguous and distinct.

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 by naming the tool's purpose and scope. It does not explicitly name alternatives, but the limitation 'No confirma registro ante RENAPO' informs when not to use it (if official registration confirmation is needed). This is a clear contextual signal, though it stops short of naming a specific sibling alternative.

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