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

Adds genuinely new behavior beyond the annotations: determinism (same input, same output) and hard limits (64 KB JSON input, 1 s per call, 1 MB result). The side-effect sentence partly restates readOnlyHint=true and openWorldHint=false, but the determinism and limit disclosures are real value-add for an agent planning a call.

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?

Purpose is front-loaded and each sentence carries content, but the entire description is duplicated in Spanish and English, roughly doubling length without adding information. The Spanish 'No para' clause even contains a garbled translation artifact ("adds,ing subtracts"), which adds noise.

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?

With an output schema present, annotations covering safety and idempotency, and 100% schema coverage, the remaining gaps an agent would care about are covered: when to use, when not to, determinism, and execution limits. Nothing needed for a correct call 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%, so baseline is 3, but the description adds semantics the schema cannot: the denominator bound is what defines the approximation ("denominador acotado") and the example shows the returned form 355/113 under the default bound. It does not name the parameters literally, but the meaning of max_denominator is clarified.

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 ("Encuentra la fracción más cercana a un decimal"), names the algorithm (continued fractions) and gives a concrete example (3.14159 → 355/113). It also explicitly distinguishes itself from the sibling fraction-arithmetic, so an agent can route 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?

Uses an explicit Cuándo / No para structure: use it when a numeric result must be exact or reproducible rather than estimated, and route to fraction-arithmetic for operations between two fractions. This is exactly the when/when-not/alternative pattern, with only the fraction-simplify sibling left unmentioned.

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