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

Annotations already cover read-only, idempotent and closed-world behavior, so the description is not obligated to repeat safety traits. It goes beyond them by disclosing pricing and payment mechanics ('$0.05 per successful call, paid over x402 (USDC on Base)') and by describing the return payload (neighbouring cells, bounding box, centre, error bounds in metres), which the annotations cannot 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?

Two dense sentences with the operation defined first, followed by the return shape and then the payment constraint; nothing is padded. It is slightly packed with parenthetical detail, but every clause carries information an agent needs.

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 no output schema, the description steps in to explain return values (bounding box, centre, error bounds, neighbouring cells), and annotations already carry the safety profile. Pricing, defaults and the encode/decode branch are all covered, leaving nothing essential missing for correct invocation.

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 op, lat, lon, geohash and precision are already fully documented with ranges, defaults and accepted values. The description restates the encode/decode duality and precision but adds no syntax or format detail beyond the schema, so the baseline of 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 specific verbs and resources ('Encode a WGS-84 latitude and longitude to a geohash', 'decode a geohash back to its bounding box, centre point and error bounds'), which clearly separates it from siblings like geo_pluscode and geo_distance. An agent knows exactly what the tool produces without opening the 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 gives a concrete use case ('proximity search over a geohash-indexed store without a spatial database'), which implies when the encode+neighbour path is appropriate. It never names an alternative tool or states an explicit when-not condition, so selection against geo_distance or geo_pluscode is left to inference.

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