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

With no annotations, the description carries the full burden of behavioral disclosure. It clearly states what the tool checks and explicitly declares that it does not confirm the RENAPO registry, which is valuable context. It does not mention invalid-input or error behavior, so some behavioral ambiguity remains.

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 compact sentences, front-loaded with the core action and scope, followed by billing and limitation context. Every sentence earns its place and there is no repetition or 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 description covers purpose, billing context, and the key RENAPO limitation, which is sufficient to begin invoking the tool. However, with no output schema and no annotations, it does not describe what the tool returns or how invalid CURPs are reported, leaving a meaningful gap in the agent's understanding of the result contract.

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 has a single 'curp' parameter with no description, and the tool description does not provide a format, example, or constraints. However, 'Valida una CURP' plus the enumerated validation steps makes the expected input reasonably clear. A format example or length requirement would add meaningful value.

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') with a specific resource ('CURP') and enumerates the exact validation aspects: formato, dígito verificador, and decodificación. The closing exclusion about RENAPO clearly distinguishes it from broader verification tools among the siblings.

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?

Provides clear context ('Incluido con saldo de paquete') and an explicit when-not ('No confirma registro ante RENAPO'), telling an agent not to use it when registry confirmation is required. It stops short of naming a specific alternative sibling, so it does not fully meet the 5-level bar.

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