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

Beyond the annotations (destructive, non-idempotent), the description discloses irreversibility, the deadline constraint, the confirmation requirement, and the asynchronous pattern — returns an operation that must be tracked via acompanhar_operacao with processando → concluida/falhou states. That is substantive behavioral context the annotations cannot convey.

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?

Three short sentences, front-loaded with the action and its key constraint, then the safety warning, then the follow-up path. No 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?

For a destructive mutation with no output schema, the description covers the return shape at a high level (an operation handle) and the tracking workflow. The remaining gap is the unexplained 'origem' and 'justificativa' parameters, which an agent could get wrong.

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 coverage is 50%: motivo's enum and nota_id's UUID format are already documented in the schema. The description says to confirm 'número, tomador, valor' and 'motivo' but adds nothing about 'origem' (local/importada) or the optional 'justificativa' (15–255 chars), so it only partially compensates for the coverage gap.

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 and resource ('Cancela uma nota emitida') plus a scope constraint ('dentro do prazo do Emissor Nacional'), which clearly separates it from emitir_nota and listar_notas 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?

Gives the operative precondition (within the National Issuer deadline) and instructs confirming nota details and motivo with the person before calling. It does not name explicit alternatives or when-not-to-use cases beyond the deadline, so it stops short of full routing guidance.

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