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

With no annotations present, the description carries the full burden. It does add real behavioral context — the upstream provider (Nominatim) and the pricing/trial constraint of 5 free calls per signed wallet — but omits what happens on no-match or multiple matches, whether results are cached, and any rate limiting.

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 with the action and the provider, and only three short sentences. The free-trial note is a useful trailing detail rather than filler.

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?

A lookup tool with four undocumented parameters and no annotations or output schema needs more than this. Return shape is summarized only as "latitude and longitude," and the critical question of which of the four input fields to use is left unresolved.

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 0% across four optional parameters, so the description must compensate. "Provide query or address" gestures at two of the four names but says nothing about q/input, whether any parameter is required, or what happens if several are supplied — a significant ambiguity for an all-optional, all-similar schema.

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: geocode a place name or address into coordinates, and names the data source (OpenStreetMap Nominatim). It distinguishes itself in kind from x402-reverse-geocode, though it never names that sibling explicitly.

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?

"Provide query or address" implies the intended input and thereby the usage context, but there is no stated when-to-use/when-not guidance and no routing to alternatives such as x402-reverse-geocode, x402-address-parse, or x402-ip-geo.

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