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

With no annotations provided, the description carries the behavioral burden and mostly meets it: it discloses the tax rates (20% up to US$50, 60% with US$20 discount above), the 17% ICMS 'por dentro', and the Central Bank exchange rate conversion. It does not state the output format, but the calculation behavior is clearly 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?

The description is dense but well-organized: purpose and rates are front-loaded, then required and optional parameters. Each sentence carries useful information, though the rule details could be more structured for easier parsing.

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 tax calculation rules are fully explained, but there is no output schema and the description does not state what the tool returns (e.g., tax amount in BRL). Edge cases like values over US$3,000 or invalid inputs are also unaddressed, leaving minor gaps for an agent.

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 baseline is 3. The description restates which parameters are required vs optional and advises using exact English names, but it adds no new semantic meaning beyond what the schema already documents for each field.

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 states a specific verb and resource ('Calcula o imposto de compra internacional') and gives concrete examples (Shein, AliExpress, Amazon). It distinguishes itself from sibling calculators by focusing on import tax rules, so an agent can tell it apart from other calculate_* tools.

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 provides clear context for when to use the tool: international purchases under Remessa Conforme, with the relevant tax brackets. It does not name alternatives or explicitly state when-not-to-use, but the domain is sufficiently constrained to guide selection.

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