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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds determinism ('misma entrada da la misma salida') and concrete limits (64 KB input, 1 s per call, 1 MB result), which is useful. But 'solo lectura, sin red, sin estado guardado' largely restates the readOnly/openWorld annotations rather than adding new behavioral context, so the extra value is moderate.

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?

Well front-loaded with the core format stated first, then labeled sections for When/Not-for/Side-effects/Limits. Slightly undermined by the trailing partial EN restatement and the 'inputSchema.description' cross-reference, which add a little redundancy but the structure remains scannable.

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 small, pure formatting tool with an output schema handling return values, the description is complete: it explains purpose, alternatives, side effects, determinism and limits. Nothing an agent needs to invoke it correctly 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 all three parameters are already documented in the schema. The description mentions 0/2 decimals and the optional COP code, but this duplicates schema content without adding syntax or edge-case detail beyond it. Baseline 3 applies when the schema does the heavy lifting.

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 (formatea) and resource (valor en pesos colombianos) with a concrete output example ($ 1.234.567, dot thousands, comma decimals), and explicitly names the sibling it is not (currency-format). An agent can distinguish it from currency-format and number-format-locale without reading schemas.

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?

Provides an explicit 'Cuándo' section (Colombian rules: DIAN, Ley Emiliani, IVA, GMF, UVT, invoicing/payment flows) and a 'No para' section that routes to currency-format for ISO 4217 locale formatting. Both when-to-use and when-not are stated with a named alternative.

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