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

Annotations already cover read-only, idempotent and closed-world, yet the description still adds substantive facts: no network access, no stored state, deterministic output, and concrete limits (64 KB input, 1 s per call, 1 MB result). It also warns that short codes are rejected, which is a behavioral constraint not encoded anywhere in the schema.

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 purpose, then conditions, then effects and limits, with zero filler. The Spanish and English versions duplicate the same content, which is defensible for bilingual callers but does double the length.

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?

An output schema exists, so return values need no elaboration, and the description still names what comes back (center plus bounding box). With one parameter, complete annotation coverage and stated limits, an agent has everything needed to call this correctly.

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 the single parameter is already documented as a required string up to 20 chars with an example. The description adds meaning beyond the schema by clarifying that only FULL codes are accepted and that short codes requiring a reference location will be rejected — a semantic constraint the schema does not express.

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: decodes a full Open Location Code into center lat/lon and bounding box, and explicitly rejects short codes. The scope boundary against plus-code-encode is named directly, so an agent can distinguish it from the sibling without inspecting 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?

Contains explicit 'When' (computing coordinates, distances, bearings, areas from given points) and 'Not for' (encoding lat/lon as a global plus code, naming plus-code-encode as the alternative). This is the full when/when-not/alternative triad.

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