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

No annotations are provided, so the description carries the burden of behavioral disclosure. It mentions the outputs (effective rate and monthly value) and the computation basis, but does not disclose potential side effects (likely none), rounding behavior, or tax bracket assumptions. For a pure calculation tool, this is acceptable but not detailed.

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, front-loaded with the core purpose and then parameter guidance. It avoids filler and each sentence adds useful information. It is efficiently structured for quick agent scanning.

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 simple two-parameter calculator with full schema coverage and no output schema, the description covers the purpose, the parameters, and the output nature. It clarifies what the result provides (effective rate and monthly amount) without needing an output schema. It is sufficient for correct invocation, though it lacks explicit return format details.

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?

The schema already provides complete descriptions for both parameters, including the enum for annex and the positive revenue requirement. The description repeats the mandatory/optional status and adds a naming hint, but does not add deeper semantic meaning beyond the schema. With 100% schema coverage, the baseline 3 is appropriate.

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 action ('calcula imposto') and the resource ('Simples Nacional'), specifying the basis ('por faixa de faturamento e anexo') and the outputs ('Alíquota efetiva e valor mensal'). It is specific enough to distinguish Simples Nacional from sibling tax calculators, though it doesn't explicitly name alternatives.

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 direct guidance on required and optional parameters and instructs the agent to use exact English parameter names, which helps avoid invocation errors. However, it does not mention when to prefer this tool over similar ones like calculate_mei_tax or calculate_late_das, nor any exclusions or prerequisites beyond the parameter requirements.

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