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

No annotations are provided, so the description carries the behavioral disclosure burden. It compensates well by explaining the calculation method (embedded interest derived via TIR) and the key modeling assumption that fees and insurance deducted from the released amount are incorporated into the rate. A minor gap is the lack of output format or units, but the core behavior is transparent.

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 sentences, each earning its place: the first states the purpose and inputs, the second explains the TIR methodology and fee handling, and the third gives usage and naming guidance. It is front-loaded, compact, and free of 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?

Inputs are fully defined by the schema and the method is clearly explained, but there is no output schema and the description does not state what the tool returns (e.g., CET as a percentage, decimal, annual rate). For a calculation tool, that return-format gap leaves the description slightly incomplete.

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 the schema already documents net_received, installments, and installment_value. The description adds a useful naming instruction ('Use exatamente estes nomes, em inglês') and restates the meaning of net_received, but does not meaningfully extend the parameter semantics beyond the schema.

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's purpose: calculate the CET (Custo Efetivo Total) of a credit proposal from the borrower's perspective, using net amount received, number of installments, and installment value. This is a specific verb plus resource, and the mention of TIR and fee treatment distinguishes it from other calculate_* 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?

The description provides clear usage context: it explains the borrower-facing inputs and even instructs the agent to call the tool twice to compare proposals. It does not explicitly name alternative tools or exclusion conditions, but the context is clear enough for correct selection among many financial calculators.

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