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

Annotations only declare openWorldHint, so the description carries real weight and delivers: it spells out the validation chain (ICP-Brasil roots, CNPJ match, CRL revocation check, ATIVA status), the issuance result (90 days, Ed25519-signed), and that the call is free. It omits failure behavior and error semantics, but that is a minor gap against a strong disclosure.

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?

Front-loaded with the most decision-relevant fact ('Free'), then the action, then the validation/issuance semantics in dense but readable sentences. No filler, though the run-on middle sentence packs many clauses.

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?

With no output schema and minimal annotations, the description does the work an agent needs: it clarifies the validation chain and what is produced. The main gap is that it never disambiguates against kya_renew_prove, an identical-shaped sibling, leaving selection ambiguity.

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%, so all four parameters are already documented (challenge_id source, credential_id UUID, both signature formats). The description adds only the high-level framing 'both signatures', so the baseline 3 is appropriate.

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 states a clear resource and outcome: it takes the two challenge signatures, validates the e-CNPJ chain, and issues a credential. That is specific enough for an agent to know this is the proof/issuance step. It does not, however, contrast itself with the very similar sibling kya_renew_prove, so an agent must infer which one applies when.

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?

It gives invocation guidance ('Send both signatures of the challenge') and implicitly positions itself as the step after kya_register/kya_renew via the challenge_id parameter. But it never states when to call this versus kya_renew_prove, or the prerequisites (that a challenge/credential must already exist from register).

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