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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still adds genuinely new behavioral facts: determinism (same input → same output) and concrete resource limits (64 KB JSON input, 1 s per call, 1 MB result), which annotations do not express.

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?

Each language block is front-loaded with the action first, then when/not-for/effects/limits, and no sentence is filler. The full duplication across Spanish and English doubles the length, but that serves locale parity rather than padding.

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 and full schema coverage, the description need not explain return values, and it covers determinism, side effects and operational limits. The only shortfall is the overbroad 'when' clause pointing at distance/bearing computations, which may mislead selection.

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% and every parameter has bounds, defaults and examples, so the schema carries parameter meaning. The description only repeats the 1-12 precision range and notes the cell-size output, adding no new syntax or format detail — 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?

The description gives a specific verb (encodes) and resource (latitude/longitude → geohash string), including the precision range 1-12 and the extra output (cell size in metres). It explicitly names the sibling geohash-decode as the opposite operation, so an agent can separate the two without opening 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?

It follows a clear when/when-not/alternative structure and explicitly routes decoding to geohash-decode. However the stated 'when' — computing coordinates, distances, bearings or areas — describes capabilities this tool does not have (those belong to geo-haversine, geo-bearing, geo-distance siblings), which can mis-select the tool for distance work.

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