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

Goes well past the annotations by disclosing the two response branches: a pedido to be tracked, or a blocker payload with code, mensagem and acao. It also explains the idempotency mechanism behind idempotentHint=true (repeating the same referencia returns the same pedido, never double-issues) and warns of real fiscal effect. It does not cover permission/credential prerequisites or what an "incerta" state requires next.

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?

Verb and resource lead, then the branch behavior, then the idempotency rule, then the confirmation warning; every sentence carries operational information and the parenthetical examples do real work.

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?

For a 9-parameter mutation with no output schema, the description supplies the missing return-value semantics (pedido vs bloqueios with their fields) and the escalation path via acompanhar_pedido, which is exactly what an agent needs to call and then handle the result.

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?

With 100% schema coverage the baseline is 3, but the description adds real semantics the schema lacks: referencia must be unique per nota the person wants issued, and reusing it collapses to the same pedido. The confirmation-related parameters (confirmo_repeticao, permitir_repetida_de) are only partly addressed, so it stops short of 5.

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?

Names a specific verb and resource ("Emite uma nota fiscal de serviço no Emissor Nacional") and constrains the target ("para um tomador já cadastrado"), which cleanly separates it from criar_tomador, listar_notas and cancelar_nota.

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?

Explicit prerequisites (use listar_tomadores or criar_tomador first), explicit follow-up (acompanhar_pedido until autorizada/recusada/incerta), explicit confirmation duty before calling, and the condition that switches behavior (com bloqueio vs sem bloqueio). Nothing about when to call is left to inference.

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