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

With no annotations, the description carries the behavioral burden. It goes beyond a tautology by disclosing the calculation basis (15% on net annual gains above the IRPF exemption) and the legal foundation. It stops short of describing the return contract, but the core behavior is well disclosed.

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?

Two dense sentences with the key formula front-loaded and parameter instructions after; no filler or redundant explanation.

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 deterministic calculator with two scalar inputs, the description plus schema is sufficient to select and invoke correctly. The only mild omission is the explicit output shape or zero-loss behavior, but no output schema exists and the computed value is strongly implied.

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?

Both parameters already have full Portuguese schema descriptions with units (R$), so the description adds limited semantic value. It reinforces that the names must be used exactly and that they are mandatory, but this largely duplicates the schema's required array.

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 uses a specific verb ('Calcula'), names the resource ('imposto sobre prêmios de apostas esportivas e bets'), and even states the rate and legal basis (Lei 14.790). This clearly distinguishes it from the many other calculate_* tax 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?

It clearly identifies the intended context — annual betting/gambling prize taxation — and explicitly designates the two required parameters. It does not name alternatives or exclusions, so it falls short of full when/when-not guidance.

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