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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and closed-world, so the safety profile is covered. The description adds value beyond that by disclosing the return payload ('fuentes oficiales y el link a la calculadora web') and the legal basis of the computation, which since there is no output schema is genuinely useful.

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 core purpose is front-loaded in the first clause, and the country-specific detail follows logically. It is dense with legal citations but each clause maps to an actual computation branch, so little is wasted; only the article numbers could be trimmed.

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 9-parameter, no-output-schema calculation tool with full schema coverage, the description supplies what the schema can't: the legal regimes, the fine components, and the shape of the return. The only remaining gap is guidance on the conditional/optional parameters, which the description leaves entirely to the schema.

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 each of the 9 parameters is already documented in the schema, giving the baseline of 3. The description adds calculation context (the 0.1% sales base in Ecuador, the 4%-14% plus 1.5% monthly in Paraguay) but does not clarify parameter interactions such as when noTax, sales, or causado become required.

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?

States a specific verb and resource (calculate late-filing fines, default interest, and total payable) with the exact legal regimes covered (Ecuador SRI art. 100 LRTI, Paraguay DNIT art. 171 Ley 125/91). This clearly separates it from siblings like calcular_multas_lavado_activos or calcular_impuesto_renta without needing to open the schema.

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?

Usage is only implied through the scenario wording ('por declarar o pagar tarde'), so an agent can infer it applies to overdue filings/payments. However, it never explicitly names when to prefer a sibling tool, nor what preconditions are needed (e.g., that country must be py or ec), leaving routing to inference.

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