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

Annotations already declare read-only, idempotent, closed-world, non-destructive, so the safety restatement adds little. The description does earn credit for genuinely new behavioral facts: deterministic output, word-boundary trimming to max length, and concrete limits (64 KB input, 1 s per call, 1 MB result) that an agent cannot infer 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?

Well front-loaded: the operation comes first, then when/when-not, then effects, determinism and limits. It is somewhat bloated by the full EN restatement of the ES text and by the vague "exactitud" usage sentence, so it is not maximally 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?

Rich annotations, 100% schema coverage and an output schema mean the description need not explain return values; given that, it covers everything an agent needs — transformation semantics, the sibling alternative, side-effect profile, determinism and hard limits.

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, but the description adds real semantics for max_length by explaining that truncation happens at a word boundary, and it clarifies that lowercase/separator are applied as part of a fixed transliteration-then-replace pipeline rather than arbitrary tweaks.

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 and enumerates the transformation pipeline: strip accents, transliterate ligatures to ASCII, lowercase, replace non-alphanumerics with a separator, trim at a word boundary. It also names the sibling it is not (es-slug, which collapses ñ into n), 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?

The "No para" line is precise: it names the actual alternative (es-slug) and the exact condition that selects it (Spanish text where ñ must be preserved). The "Cuándo" line, however, is generic boilerplate ("transform, compare or measure text exactly") that does not really help an agent decide when a slug tool is the right pick.

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