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

With no annotations, the description carries the burden of behavioral disclosure. It does reveal the formula M = C × (1+i)^n and the existence of periodic deposits, which is helpful. However, it does not specify how deposits are timed, how annual_deposit_growth is applied, what the output shape is, or other edge-case behaviors.

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 three sentences with no filler: the main action comes first, then the formula, then a concise parameter list and naming rule. Every sentence earns its place and answers a practical question.

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?

The tool has no output schema and no annotations, yet the description never states what the tool returns (e.g., final amount, JSON object, projection). It also leaves deposit timing and annual growth behavior unexplained. For a financial calculator with 5 parameters, these gaps make the definition incomplete for reliable use.

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 baseline is 3. The description adds value by explicitly enumerating required vs optional parameters and instructing the agent to 'Use exatamente estes nomes, em inglês', guarding against translation errors. It still does not elaborate on the meaning of annual_deposit_growth beyond what the schema provides.

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 'Calcula juros compostos com aportes mensais', naming a specific verb, calculation type, and differentiator (monthly deposits). The formula and the listed parameters make clear it is compound interest with periodic contributions, which separates it from siblings like calculate_simple_interest and other calculators.

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 states the required and optional parameters, but it does not explicitly say when to prefer this tool over alternatives or when not to use it. Usage context is implied by the phrase 'juros compostos com aportes mensais' rather than stated directly.

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