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

No annotations are present, so the description carries the disclosure burden. It does disclose the key behavioral traits: the calculation includes all listed cost components, is bounded by an income ratio cap, and returns two values. It does not mention assumptions or default behaviors beyond what the schema shows, but for a calculator the core behavior is transparent; no contradiction.

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?

The description is two sentences: purpose+output first, then parameter list. It is front-loaded and compact, though the explicit parameter list duplicates schema information. No filler or marketing language.

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 8-parameter calculator with no output schema, the description explains the calculation inputs, cost scope, and output, but it lacks a comparison with the closely related sibling calculate_car_ownership_cost and does not specify the return format in detail (e.g., units, failure case). Overall it is adequate but not complete for disambiguation.

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?

Input schema already covers all eight parameters with descriptions (100% coverage), so the baseline is 3. The description merely lists which parameters are required vs optional and insists on English naming, adding no semantic information 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 opens with a specific verb and resource ('Calcula que preço de carro cabe numa renda') and clarifies it accounts for total ownership cost (prestação, IPVA, seguro, manutenção, combustível) and returns the affordable price and remaining installment. This distinguishes it from plain financing calculators and from the sibling calculate_car_ownership_cost, though it does not name that tool explicitly.

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 gives no guidance on when to prefer this tool over alternatives such as calculate_car_ownership_cost or calculate_financing. Usage is only implied by the stated purpose, and the only explicit instruction (use exactly these English parameter names) is about parameter usage, not tool selection.

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