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

Annotations already convey read-only, idempotent, and non-destructive behavior; the description adds that it corrects installments, applies interest/fine/fees, and returns a per-installment breakdown and totals. It also discloses important legal traps. 'Atualização' here means monetary correction, not a mutation, so there is no contradiction with readOnlyHint.

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 dense sentences with no filler: purpose, output, then critical caveats. The front-loaded warning about SELIC and IPCA legal regime earns its place because it prevents a common calculation error.

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 an 11-parameter tool with no output schema and no parameter descriptions, the description is largely complete: it gives the domain, the input concepts, the return shape, and the legal regimes that control valid invocations. It could still detail how ABATIMENTO_PAGAMENTO is treated and what the default option values are, but the essential information to select and invoke the tool correctly is present.

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 zero schema descriptions, the description supplies the missing semantics for the most important parameters: 'índice oficial' maps to indice; 'juros, multa e honorários' map to their corresponding fields; 'parcelas' is the required array. It also tells the agent how legal rules should affect parameter choices. Some parameters (pro_rata, multa_incide_sobre_juros, honorarios_tipo) are not individually explained, but the core invocation is covered.

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 names the exact calculation: 'Atualização monetária / liquidação de débito judicial' and specifies the operation 'corrige parcelas por um índice oficial', followed by juros, multa and honorários. It also states the return shape (detalhamento por parcela e totais), making it distinguishable from sibling calculo_* tools at a glance.

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 clear usage context: judicial debt settlement. The legal-regime warnings are actionable guidance for configuring indice, juros, and taxa_juros (SELIC already includes correction plus interest; post-September/2024 civil uses IPCA + legal rate). It does not explicitly name excluded sibling tools, so it stops one step short of a full when-not-to-use statement.

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