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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description usefully adds that the data is public and requires no API key, which is real operational context an agent needs before invoking.

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?

Three short fragments, front-loaded with what the tool returns and scoped immediately. Nothing wasted, though the telegraphic style leaves little room for the missing parameter and usage detail.

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?

A simple two-parameter lookup tool, so a brief description is defensible, and no output schema exists to relieve it of explaining returns. However, with zero schema coverage on parameters, the definition leaves an agent guessing about year and category values.

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 0%, so the description carries the full burden for the two parameters. '(todos o por categoría)' vaguely gestures at the categoria filter, but anio, its default, the category vocabulary, and the maxLength=40 constraint are all undocumented in both schema and description.

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?

Names a specific resource (gastos deducibles del IRPF del autónomo) and its scope (todos o por categoría), so an agent can tell it returns deductible-expense data rather than a calculation. Sibling differentiation is only implicit — no explicit contrast with cuota_irpf or escala_irpf — but the resource is concrete.

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?

There is no statement of when to use this tool versus alternatives such as cuota_irpf or obligaciones_fiscales, and no prerequisites or exclusions. 'Datos públicos. Sin clave.' tells the agent it can call freely but not when it should.

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