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

Annotations already cover read-only, idempotent, non-destructive and closed-world, and the description still adds real context beyond them: no stored state, determinism, 12 significant digits precision, and hard limits (64 KB input, 1 s per call, 1 MB result). The one gap is error behavior — it doesn't say what happens if "to" or "from" names an unsupported unit.

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 and well-ordered (purpose, default behavior, when, not-for, side effects, limits), but the entire body is duplicated verbatim in Spanish and English, roughly doubling token cost with no new information.

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 three-parameter pure conversion tool with full annotations and an output schema, nothing needed to call it correctly is missing: unit vocabulary, default for "to", precision, side effects and resource limits are all stated.

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%, with per-parameter descriptions and examples for value and from, so the baseline of 3 applies. The description reinforces the unit vocabulary and the "omit to => all units" default, but adds little that the schema does not already state.

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 velocidad entre unidades") and enumerates the supported units (m/s, km/h, mph, kn, ft/s), which pins down scope exactly. It also names the sibling it is not (convert-acceleration), so an agent can distinguish it without opening another 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?

Explicit "Cuándo" section gives the selecting condition (converting a quantity between units with exact definitional factors) and an explicit "No para" exclusion that routes to convert-acceleration. Nothing is left to inference.

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