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

Annotations already declare readOnlyHint, openWorldHint=false, idempotentHint and destructiveHint=false, so the safety profile is covered; the description still adds operational limits (64 KB input, 1 s per call, 1 MB result), 'sin red, sin estado guardado' and determinism, which are not in the annotations. It does restate read-only/idempotent in prose, so it is additive rather than fully independent.

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 label-structured (Cuándo / No para / Efectos / Determinista / Límites), which aids scanning, but the whole block is duplicated: the English half is explicitly the same text as inputSchema.description, and 'Determinista' largely restates idempotentHint. Redundancy costs it here.

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?

With one optional parameter, full schema coverage, an output schema carrying return values, and annotations covering the safety profile, the description supplies everything an agent needs: what is queried, how, when to choose it, the sibling to avoid, and hard limits. Nothing material 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%, giving a baseline of 3, and the description still adds meaning beyond the schema: name matching is accent-insensitive and the 5-digit form is interpreted as a municipality code prefix (schema only shows '05, 05001, antioquia'). It stops short of describing matching/precedence behavior when a query matches multiple departments.

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: looks up Colombia's 33 DIVIPOLA department-level codes by code, name or 5-digit municipality prefix, returning capital and municipality code. The scope (32 departments + Bogotá D.C.) and the accepted key forms are explicit, so an agent can distinguish it from any of the hundreds of sibling lookup tools.

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' clause (applying a Colombian rule exactly: DIAN, Ley Emiliani holidays, COP, IVA, GMF, UVT, e.g. invoicing/payment flows) and an explicit 'No para' clause naming the alternative sibling iso-country-lookup and the exact disambiguation criterion (ISO 3166-1 country codes vs. Colombian departments). When-to-use, when-not-to-use and the alternative are all present.

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