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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so some prose ("solo lectura, sin red, sin estado guardado") restates structured data. What is genuinely additive are the hard limits (64 KB JSON input, 1 s per call, 1 MB result) and the 12-significant-digit output precision, which no structured field carries.

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?

Content is front-loaded with the core verb, units and the omit behavior before usage, side effects and limits. The Spanish/English duplication roughly doubles the length, but each language block is tight and the parallel structure makes scanning easy.

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 simple 3-parameter pure-conversion tool with an output schema already describing the return shape, the description covers units, exactness, deterministic behavior, timeouts, size caps and the sibling alternative. An agent has everything needed to call it correctly.

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% and the schema already documents all three parameters, including "omit for all" for `to` and the unit list for `from`. The description's "Sin 'to' devuelve todas" is a useful behavioral reinforcement but largely duplicates the schema, so the baseline 3 applies.

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 (converts frequency), enumerates the supported units (Hz, kHz, MHz, GHz, rpm, bpm), and explicitly contrasts with the nearest sibling convert-time. An agent can identify this tool 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?

"Cuándo: hay que convertir una cantidad entre unidades con factores de definición exactos" gives the triggering condition, and "No para: convertir tiempo entre unidades (convert-time)" names the exclusion and the alternative tool by name, which is the routing decision an agent actually needs.

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