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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds value beyond that with determinism, explicit limits (64 KB input, 1 s per call, 1 MB result) and a no-network/no-state statement, which are all operational facts an agent cannot derive 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?

The front-loaded purpose, trigger, exclusion and limits are well ordered and easy to scan. However, the entire block is duplicated in Spanish and English, roughly doubling length for no informational gain, and the 64 KB claim is redundant with (and contradicts) the schema's 4096 limit.

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?

An output schema exists, so return-format detail is not required. The description still covers everything else an agent needs for a one-parameter, deterministic transform: tokenization behavior, Unicode handling, determinism, side effects and resource 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% and the single parameter is fully described, so the baseline is 3. The description adds the useful splitting semantics, but it also introduces a conflicting limit: the schema caps text at maxLength 4096 while the description advertises 'entrada JSON de hasta 64 KB', which could mislead an agent about the real ceiling.

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 ('convierte texto o un identificador a snake_case') and goes further by spelling out the tokenization rules (spaces, punctuation, camelCase/acronym boundaries, Unicode preserved). It explicitly separates itself from the case-detect sibling, so an agent can distinguish it 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?

Provides an explicit 'Cuándo' trigger (transform/compare/measure text exactly) and an explicit 'No para' exclusion pointing to case-detect as the alternative. This is the when/when-not/alternatives pattern done properly.

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