ある年・流れ・品目の、国ごとの数量と金額（円）を返す。partner を書けばその国だけ。partner に「世界の合計」と書けば全体。
| Name | Required | Description | Default |
|---|---|---|---|
| hs | Yes | 品目の番号。例：8903（船の合計）・890332（モーターボート 7.5〜24m）・890322（セールボート 7.5〜24m）・840721（船外機）・8902（漁船）。一覧は list_codes | |
| flow | Yes | import＝日本の輸入・export＝日本の輸出 | |
| year | Yes | 年（2011〜2025） | |
| partner | No | 相手の国の日本語名（例：アメリカ・フランス・中国・韓国・タイ）。省くと全部の国 |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It usefully discloses that the tool returns quantity and value in yen and that partner filtering is optional, but it does not describe output structure, quantity units, data source, or any permission/rate-limit 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 two compact sentences with the main return behavior front-loaded and the optional partner behavior immediately after. There is no wasted wording.
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 the fully described four-parameter schema and the absence of an output schema, the description is largely complete: it names the returned quantity/value data and explains partner filtering. The main omission is sibling-tool routing, which is relevant because top_partners and yearly_series appear to cover related trade queries.
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 the schema already documents year, flow, hs, and partner. The description adds a useful special partner value, “世界の合計,” for overall totals, but otherwise adds little beyond the 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?
The description states a specific action and resource: it returns quantity and yen value by country for a given year, flow, and HS item. This is clear enough for an agent to understand the tool, but it does not distinguish get_trade from related siblings such as top_partners or yearly_series.
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 explains how to use the optional partner parameter, but it gives no guidance on when to choose get_trade instead of sibling tools like top_partners or yearly_series. There are no explicit alternatives, prerequisites, or exclusion conditions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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