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

Annotations already declare readOnly, idempotent, non-destructive, so safety is covered; the description adds real behavioral context: the exact formulas applied per operation, the rounding to centavos, and the return shape (importe sin IVA, IVA, importe con IVA). It does not mention validation limits such as the maximum monto, but that gap is minor.

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?

Front-loaded with the core action, then operation semantics, then exclusions and return values; no filler. It is dense but each sentence carries operational information; the rate sentence overlaps slightly with the tasa parameter description but is acceptable.

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?

With no output schema, the description compensates by specifying the three returned fields and their rounding. Exclusions and supported rates are also stated, leaving nothing essential unknown for a 3-parameter calculation tool.

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 coverage is 100 %, so the baseline is 3; the description goes beyond by explaining what each operation value does arithmetically and by noting which rates exist (16 % general, 8 % frontera) plus which cases are out of scope. It adds meaning rather than repeating 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?

States a specific verb and resource (calcular el IVA de México sobre un importe) and immediately enumerates the three operations it supports with their formulas. The sibling tools are all distinct calculators (inflación, liquidación, pensión, sueldo neto), so the resource alone clearly separates it.

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?

Explicitly defines when each operation applies («agregar»: el monto NO trae IVA; «quitar»/«desglosar»: el monto YA trae IVA) and states exclusions: no retenciones, no tasa 0 % ni exenta. This is exactly the when/when-not guidance an agent needs.

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