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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, and the description still adds real value: determinism, no network, no stored state, and concrete limits (64 KB input, 1 s per call, 1 MB result). These operational constraints are not derivable from 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?

Front-loaded with the core action, then when/not-for/effects/limits in a scannable order. The full Spanish and English duplication is redundant for a single agent, costing some length, though each version is individually tight.

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?

Covers purpose, exclusions, side effects, determinism, and hard limits, and an output schema exists so return values need no explanation. Nothing an agent needs to call it correctly 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 coverage is 100%, so the baseline is 3; the description goes further by explaining that width is measured in graphemes and that over-width words are split only when break_long_words is true. That adds behavioral meaning beyond the schema's terse field descriptions.

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 ('Ajusta texto a un ancho máximo de línea') plus the key mechanism (graphemes, at spaces, preserving existing line breaks). It explicitly names the sibling it is not (text-truncate), so an agent can distinguish it without opening either 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?

Gives an explicit 'Cuándo' condition (exact transform/compare/measure rather than approximation) and an explicit 'No para' exclusion pointing to text-truncate. The alternative and the condition that selects it are both named.

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