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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: 'Gratis' (no cost) and 'no guarda nada' (no persistence), plus the shape of the result ('un semáforo por requisito con qué falta'). This meaningfully supplements the annotations.

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 tight sentences with zero filler: purpose and scope first, then return format, then cost/persistence caveat. Every sentence earns its place and the most important information is front-loaded.

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 single-parameter, no-output-schema, read-only validation tool, the description covers purpose, the return concept ('semáforo por requisito'), and the no-persistence/free behavior. It doesn't address edge cases such as what happens with text below the 80-character minimum, but nothing essential for calling it is missing.

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% (the single 'texto' parameter is documented as 'Texto íntegro del burofax' with min/max length constraints), so the baseline is 3. The description reinforces that the input is a full, already-written text but adds no syntax or format detail 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?

States a specific verb (evalúa/valida) and resource (un burofax ya escrito) against a concrete standard (los cinco requisitos del intento de negociación de la Ley 1/2025), even enumerating the five criteria. The phrase 'ya escrito' implicitly distinguishes it from the sibling redactar_burofax and enviar_burofax, so an agent can route correctly without opening 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?

Clearly frames the usage context: it operates on an already-written burofax, telling the agent this runs as a pre-send check rather than a drafting or sending step. It stops short of explicit exclusions or naming which sibling to use instead, so it's clear context without full when/when-not guidance.

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