運行情報（遅延・運転見合わせ）

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

No annotations are provided, so the description carries the full burden. It discloses the core read behavior and the ability to see normal operation, but it does not mention that onlyTroubled defaults to true (so by default only troubled lines are returned) or describe the output format. The parenthetical about normal operation could be ambiguous without schema details.

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 short sentences with no filler. It front-loads the main purpose (area-based operation status retrieval) and then adds the line-filter detail, making every sentence earn 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?

The tool is relatively simple, but with no output schema and no annotations, the description should clarify default behavior (e.g., onlyTroubled defaulting to true) and indicate what the response contains. It also does not position itself among siblings. These gaps make it adequate but incomplete.

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 baseline is 3. The description mentions the 'line' filter and normal status, but it largely restates what the schema already says (e.g., area-based retrieval, line filter). It adds little beyond the schema parameter descriptions.

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 uses a specific verb '取得する' (retrieve) with a clear resource '鉄道の運行情報（遅延・運転見合わせ等）' and a clear scope 'エリア別'. It also mentions line filtering and normal-operation detection, which clearly distinguishes it from sibling tools like search_station, search_route, and get_timetable.

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 provides clear context: use this tool to get railway operation status by area, optionally filtered by line. However, it does not explicitly state when not to use it or mention alternatives (e.g., use get_timetable for schedules), so it misses full guidance.

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