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

Annotations already declare readOnlyHint=true and idempotentHint=true, indicating safe read-only behavior. The description adds significant behavioral context: it lists exact return fields, notes that CPF eligibility is only an estimate and requires extra organism habilitations, and mentions replacement certifications. This goes beyond the annotations and helps the agent understand limitations and side effects.

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 efficient: three sentences including a concrete example. It front-loads the core question, then lists return values, and closes with a practical caveat. No superfluous words. The example is helpful for non-English users, but the description could be slightly tighter by moving the example to a separate field.

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 the tool has one parameter, rich annotations, and no output schema, the description covers the essential aspects: purpose, return fields, and a key limitation (CPF eligibility is not guaranteed). It does not describe the exact response structure (since no output schema), but listing the fields is sufficient for a simple lookup tool. The example adds usability context.

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 100%, with the 'numero' parameter well-documented (examples of formats, maxLength, minLength). The tool description does not add further semantic meaning to the parameter beyond what the schema already provides. Baseline 3 is appropriate given full schema coverage.

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 the tool checks if a certification is currently registered/active and provides expiry details. It lists specific return fields including status, expiry date, remaining days, and CPF eligibility. However, it does not explicitly differentiate from sibling tools like check_habilitation or get_certification, which slightly reduces clarity.

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 when to use the tool (to check registration validity of a certification) via an example question. But it gives no explicit guidance on when not to use it or when to prefer alternatives among the nine sibling tools. Usage context is present but lacks exclusionary or comparative advice.

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