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

Annotations already cover readOnly, idempotent, non-destructive and openWorld=false, so the bar is lower, yet the description adds genuinely new behavioral facts: determinism, no stored state, and concrete operational limits (64 KB input, 1 s per call, 1 MB result). The only redundancy is 'sin red', which openWorldHint=false already implies.

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 entire description is provided twice, once in Spanish and once in English, so roughly half the tokens carry zero new information for the agent. The labeled structure (Cuándo / No para / Efectos secundarios / Límites) is good, but the duplication means many sentences do not earn their place.

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 an output schema present, return values need no explanation, and the description covers inputs, determinism, side effects and resource limits — enough to call it correctly. The one weak spot is the misleading 'when to use' clause pointing at distance/bearing computation, which could send the agent to the wrong tool.

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 description coverage is 100%, so lat, lon and length are all documented, including ranges, defaults and the ~14 m granularity. The description restates the 10–15 length range but adds no new semantics (units, edge cases, behavior at minimum length) beyond the schema, so the baseline 3 applies.

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 precise verb+resource: encodes latitude/longitude into a global Open Location Code with explicit length range (10–15) and purpose (street-number-less addresses). It also explicitly names the inverse sibling plus-code-decode as out of scope, so the agent can distinguish it from that tool without reading either 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?

The 'No para' line is excellent: it names plus-code-decode explicitly with the condition that selects it. However, the 'Cuándo' line ('when coordinates, distances, bearings or areas have to be computed from given points') describes a family-level use case rather than a reason to encode a plus code — encoding does not compute distances or bearings, so that guidance is at best generic and at worst misroutes the agent to a sibling like geo-haversine.

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