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

Annotations already carry the full safety profile (readOnly, idempotent, closed-world, non-destructive), so the bar is lower. The description still adds real context by spelling out the returned coverage/source metadata, though it says nothing about error behavior or response shape.

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?

Content is dense and front-loaded, with the alternative routing placed last as a clean closer. The only cost is that the entire body is duplicated in Japanese, roughly doubling length without adding information for any single reader.

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?

There is no output schema, so the description must describe return values itself — and it does, listing every metadata field an agent would receive. Combined with the annotation coverage of side effects, nothing an agent needs to call this correctly is missing.

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% and the single `lang` parameter is fully documented in the schema, including its ja default and enum. The description contributes no additional parameter meaning, so the baseline 3 is correct.

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 enumerates exactly what is returned: latest month plus per-month status for exports and imports, the latest month common to both, first data month per level (chapters/sections from 1988), and sources. That is a specific, unambiguous statement of scope, and it explicitly separates the tool from get_catalog.

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 names the alternative and the condition that selects it: 'For which tool to use and known data gaps, use get_catalog instead.' The boundary between the two tools is stated outright, leaving nothing to inference.

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