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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, but the description adds genuinely new context: determinism ('la misma entrada da la misma salida') and concrete limits (64 KB input, 1 s per call, 1 MB result). It partly restates the read-only/closed-world profile, which is why it stops short of 5.

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 action, then when/not-for/side-effects/limits in labeled blocks that each earn their place. The cost is a full bilingual duplication that roughly doubles length without adding information an English-only reader lacks.

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, selection criteria, alternative sibling, side effects, determinism and operational limits; the output schema exists, so return-value explanation is correctly omitted. An agent has everything needed to call it correctly and predict its behavior.

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 description coverage is 100% for all three parameters, so the baseline is 3; the description goes beyond it by stating the accepted input forms (mixed numbers/decimals as well as fractions), which the schema's bare 'string up to 200 chars' does not convey. The operation enum is already fully documented in the schema, so nothing extra is added there.

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 set (suma, resta, multiplica, divide) over a precise resource (dos fracciones exactas) plus the output shape (resultado simplificado). It names the sibling fraction-simplify as the thing it is not, so an agent can route between them 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?

'Cuándo: un resultado numérico tiene que ser exacto o reproducible y no estimado' gives the selecting condition, and 'No para: simplificar una fracción ... (fraction-simplify)' names the excluded case and the alternative tool explicitly.

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