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

With no annotations, the description carries the behavioral disclosure burden. It explains the calculation model (amount received today against annual withdrawals, by IRR) and the decision context, going well beyond the tool name. It does not specify output format or caveats like assumptions of constant annual parcels, but as a pure calculator this is reasonably 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 with no filler. The core purpose is front-loaded, followed by usage context and parameter guidance. Every sentence earns its place.

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 calculator with three fully documented parameters and no output schema, the description covers the purpose, the financial scenario, and the required inputs. The main gap is not describing the output format in detail, but the term 'taxa de juros' and the comparison context make the expected result clear enough.

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 100%, so the baseline is 3. The description adds meaningful value by explicitly listing the required parameters and instructing the agent to use exactly these names in English — a critical cross-lingual detail not present in 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 specific purpose: reveal the embedded interest rate in an FGTS birthday-withdrawal advance offer using IRR. It identifies the resource (antecipação do saque-aniversário do FGTS) and the calculation method (TIR), which distinguishes it from siblings like calculate_fgts, calculate_cet, and compare_loans.

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 clear usage context: 'É a conta pra comparar a antecipação com um crédito comum antes de assinar.' This tells an agent when to invoke it, though it does not explicitly name alternatives or state when not to use it.

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