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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint, and the description correctly reinforces this rather than contradicting it. It adds genuinely new behavioral facts beyond the annotations: no network access, no stored state, determinism, a 64 KB input ceiling, a 1 s per-call budget and a 1 MB result cap. The only reason this is not a 5 is that the read-only/no-state sentences partly restate what the annotations already guarantee.

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 transformation, then organized into labeled blocks (Cuándo / No para / Efectos / Determinista / Límites), so an agent can stop reading at any point. The full bilingual duplication adds length, though this appears to be a deliberate convention for this server rather than padding.

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?

Purpose, exclusion, side effects, determinism and operational limits are all present, and a return-value contract is unnecessary because an output schema exists. For a one-parameter pure function, nothing an agent needs in order 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?

There is a single parameter and schema description coverage is 100%, so the schema already carries the meaning; the description adds nothing about the parameter itself. The only adjacent detail is the 64 KB limit, which is already encoded as maxLength in 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 transformation (lowercase everything, capitalize first letter of each sentence) including the non-obvious handling of Spanish ¿ and ¡, so the exact output shape is unambiguous. It explicitly names the sibling it is not (case-detect), which cleanly separates it from the large family of case-* tools.

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 'Cuándo' clause gives a positive trigger (exact transformation, comparison or measurement of text) and the 'No para' clause names the concrete alternative case-detect with the condition that selects it. This is an explicit when/when-not pair with a named sibling, leaving nothing to inference.

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