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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, and the description still adds real context beyond them: no network access, no stored state, determinism, 12-significant-digit precision, and concrete limits (64 KB input, 1 s per call, 1 MB result). That is exactly the extra behavioral surface an agent needs before calling.

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 and every clause (units, default behavior, when/not-for, side effects, limits) carries information. The main inefficiency is the full Spanish/English duplication, which doubles length without adding new facts, though it is a deliberate bilingual pattern.

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 3-parameter, fully documented, output-schema-backed conversion tool, nothing an agent needs is missing: units, default behavior, exclusions, safety profile, determinism, and resource limits are all present. Return-value shape is covered by the output schema, so its absence from the description is correct.

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 the baseline is 3, but the description adds the meaningful behavioral rule that omitting 'to' returns every unit — a semantic consequence the schema only hints at with 'omit for all'. It does not add unit-alias or case-sensitivity guidance, so not a 5.

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 potencia entre unidades') and enumerates the supported units (W, kW, MW, GW, hp, PS, BTU/h, kcal/h), which immediately separates it from the many other convert-* siblings. It also names the one sibling it could be confused with (convert-energy) and rules it out.

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' clause gives the triggering condition (a quantity must be converted with exact definitional factors) and an explicit 'No para' clause routes energy conversion to convert-energy. Both when-to-use and when-not-to-use are stated, not implied.

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