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

Annotations already declare readOnly, idempotent, non-destructive and openWorld=false, but the description adds genuinely new context: no network, no stored state, determinism, and concrete limits (64 KB input, 1 s per call, 1 MB result). It does not explain the error behavior for unparseable input, which keeps it below 5.

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 organized (purpose, when, not-for, effects, limits), but the same content appears three times: the Spanish block, the English block, and again in inputSchema.description which the description itself points to. That triplication is wasted context for an agent.

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 one-param, read-only parser with an output schema and full annotation coverage, everything needed is present: accepted formats, sibling exclusion, side effects, determinism and size/time limits. No return-value explanation is required since an output schema exists.

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 the single param already documents type, requiredness, maxLength and an example, so the baseline is 3. The description earns an extra point by enumerating accepted input shapes ("$ 1.234.567,50", "1,5 millones", "$3 mil", "COP 2.500"), which clarifies dot-thousands/comma-decimal and word-scale handling beyond the schema.

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 (parse/convert) and resource (Colombian-style money text) plus the output type (a number), with concrete input examples. It explicitly names the sibling it is not (es-number-parse), so an agent can discriminate without opening 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?

Has explicit "Cuándo" (when a Colombian rule — DIAN, Ley Emiliani, COP, IVA, GMF, UVT — must be applied exactly, e.g. invoicing) and "No para" routing to es-number-parse for Spanish words/digits. Both the positive and negative conditions are stated.

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