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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful context not in the annotations: the data is public and requires no API key ('Datos públicos. Sin clave.'). It says nothing about the shape of the returned brackets, but for a static lookup 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?

Three short fragments with no padding, and the core identity (what is returned) is front-loaded ahead of the access note. The telegraphic style is efficient, though it borders on under-specification rather than true concision.

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?

This is a simple two-parameter, read-only lookup with no output schema, so the description carries the burden of describing the return value (bracket thresholds and rates) and it does not. The safety and access profile is adequately covered by annotations and the 'sin clave' note, making it minimally viable but thin.

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 must compensate, and it does name both dimensions: the enum values 'general o ahorro' and the year. However, it presents 2026 as fixed ('año 2026') while the schema exposes an 'anio' parameter with a default, leaving it unclear whether other years are valid or how the year affects the result.

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 the specific resource (tramos de la escala IRPF estatal) and its two variants (general/ahorro) plus the year, so an agent knows it returns bracket tables rather than computing a tax amount. It does not, however, explicitly distinguish itself from the closely related sibling cuota_irpf, which an agent could easily confuse it with.

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 tarifa_at_ep, nor any prerequisite or exclusion. 'Sin clave' hints at access conditions but gives no invocation guidance. The agent must infer usage from the name alone.

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