Reverse geocode (lat/lon -> Japanese address)

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It usefully notes that results are based on the nearest point rather than boundary containment and mentions the underlying ReverseGeoJP API. However, it does not address failure cases, coordinate datum, result distance limits, or API error behavior.

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 description is only two sentences, front-loads the core behavior, and includes a valuable caveat. Every phrase adds information; there is no redundancy or 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?

Given there is no output schema, the description does list the essential return components (prefecture, municipality, town area, postal code) and highlights the nearest-point behavior. It lacks some edge-case details and explicit sibling differentiation, but it is sufficiently complete for a simple reverse-geocoding tool with two well-specified parameters.

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?

The input schema already provides full coverage for lat and lon, including ranges and brief Japanese labels. The description adds that these coordinates are used to find the nearest town address, but offers no extra detail about precision, units, or coordinate system, so it does not exceed the schema baseline.

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 clearly states the tool converts latitude/longitude into the nearest town-level Japanese address, listing specific components (prefecture, municipality, town area, postal code). This specific verb+resource statement distinguishes it from sibling tools like geocode, which handles the forward direction.

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 description implies usage (reverse geocoding from coordinates) via the title and the note about returning the nearest point rather than a boundary match. However, it does not explicitly state when to use this tool versus alternatives like geocode or get_parcel, nor does it name alternative tools for forward geocoding or parcel-level lookup.

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