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

With no annotations provided, the description carries the full burden, and it does disclose the two distinct behaviors: 10% withholding over R$ 50k/month and the annual minimum taxation rule for income over R$ 600k/year. It does not describe the output format or what happens when annual_income is omitted, but the core calculation behavior is 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 compact and front-loaded: the first sentence identifies the purpose and law, the second covers the two calculation rules, and the final sentence clarifies parameters. Every sentence earns its place and there is no filler.

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?

Given no output schema and no annotations, the description covers the legal basis, thresholds, required vs optional parameters, and parameter names—enough to invoke the tool correctly. The main missing piece is the return semantics, such as whether the result is a single tax amount, a breakdown, or zero when thresholds are not met.

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 input schema already explains both parameters well. The description adds the explicit instruction to use the exact English parameter names, which is helpful, but it does not meaningfully deepen the conceptual meaning of monthly_dividends or annual_income beyond 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 begins with a specific verb and resource: 'Calcula o imposto sobre dividendos a partir de 2026 (Lei 15.270)'. It goes beyond a generic label by naming the legal rule and both calculation thresholds, which clearly distinguishes it from dividend-yield, IRPF, and other 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?

The description gives clear context for when to use the tool: for dividend tax under Lei 15.270, covering the R$ 50k monthly withholding trigger and the R$ 600k annual minimum-tax rule. It does not explicitly mention alternatives or state when not to use it, but the legal and threshold context is strong enough to guide selection.

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