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

Annotations already declare readOnly/openWorld=false/idempotent/non-destructive, so the safety profile is covered; the description still adds genuinely new context: determinism, no stored state, and concrete operational limits (64 KB input, 1 s per call, 1 MB result). Only gap is that it does not state how out-of-range or missing input is handled.

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?

The Spanish text is front-loaded and well structured (When / Not for / Side effects / Deterministic / Limits), but the content is then repeated verbatim in EN and again in the schema description, roughly tripling the length for the same information. Duplication rather than size is the waste.

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?

An output schema exists, so return values need no explanation, and the description covers purpose, routing, determinism and limits. The only material omission for a 3-param, all-optional tool is the uvt-vs-pesos input-choice rule, which an agent must infer.

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% and each parameter is documented, so the baseline is 3; the description earns an extra point by giving the per-year UVT rates ($47.065 / $49.799 / $52.374), which explains what the `year` parameter actually selects. It does not clarify that exactly one of `uvt` or `pesos` should be supplied, even though both are optional with no required field — a real ambiguity left unresolved.

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 between UVT and Colombian pesos) and names the exact scope (2024/2025/2026 with the actual UVT values and the DIAN resolution for 2026). It explicitly names the sibling it is not (co-cop-format) and contrasts formatting vs. conversion, so an agent can route correctly without opening a 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" gives the positive condition (applying a Colombian rule exactly — DIAN, Ley Emiliani, COP amounts, IVA, GMF, invoicing/payment flows) and "No para" gives the exclusion with the named alternative (co-cop-format for formatting). This is explicit when/when-not/alternative coverage.

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