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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description nonetheless adds genuinely new context: explicit limits (64 KB input, 1 s per call, 1 MB result) and determinism, which the annotations do not encode.

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 ESC/EN duplication roughly doubles length for the same content, and 'Determinista: la misma entrada da la misma salida' restates the idempotentHint annotation. Content is front-loaded and organized, but a meaningful share of the text does not earn its place.

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, read-only transform with an output schema and full annotations, the description covers purpose, alternative, side effects and operational limits — nothing an agent needs in order to invoke 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% for the single 'text' parameter, so the schema does the heavy lifting. The description adds value by noting surrogate-pair handling and that the input is 'escaped text', clarifying expected content beyond the schema's terse 'Escaped text (string; required).'

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 (converts/desescapa) and enumerates the exact resource forms it handles (\uXXXX with surrogate pairs, \u{X}, \xXX, U+XXXX) plus the direction of the transform. The agent can distinguish it from unicode-escape purely from the description.

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?

Explicitly names the alternative ('No para: escapar caracteres no ASCII ... (unicode-escape)'), which is a clear routing signal. However, the positive 'When' clause ('convertir bytes o texto a esta codificación, o desde ella') is muddled and implies bidirectional conversion, which the tool does not perform — an agent could misread it.

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