Get parcel (lat/lon -> chiban)

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

With no annotations, the description carries the burden of behavioral disclosure. It reveals the underlying API (ChibanJP) and the critical limitation of only covering 8 prefectures, which is essential behavior. It also lists the output fields. It does not mention error behavior (e.g., if the point is outside the supported area or not in a parcel), but the disclosed scope is a significant transparency win.

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 two sentences, with the primary action and return contents in the first sentence, and the API source and critical area limitation in the second. There is no filler, and every sentence earns its place.

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?

For a simple two-parameter lookup, the description provides the key context: what is returned, the data source, and the geographic limitation. It does not detail error handling or coordinate system, but the simplicity of the tool and complete parameter schema mitigate that need. It is slightly below a 5 because error behavior for out-of-area points is unspecified.

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 schema fully describes both parameters (lat and lon) with ranges and labels. The description adds no additional parameter semantics beyond what the schema provides, so the baseline of 3 is appropriate per the guidance.

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 it returns the parcel number, 大字, city, and surveying accuracy for a point given lat/lon. This is a specific verb+resource combination and distinguishes itself from sibling geocoding tools by focusing on chiban data from the ChibanJP API.

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 explicitly lists the eight supported prefectures, giving clear usage boundaries. However, it does not mention alternatives like reverse_geocode for general addresses or geocode for forward lookups, so it is not fully explicit about when to choose this over siblings.

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