日付の詳細情報

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

Annotations already declare this as a read-only operation (readOnlyHint=true). The description adds valuable behavioral context by stating that omitting the date returns today's information in Japan time, which is not evident from the schema or annotations. It does not mention error handling or the exact return format, but these are minor for a read-only tool.

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, front-loaded with the core purpose, and contains no redundant or unrelated information. Every word 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 single-parameter read-only tool, the description enumerates the three return components (weekday, holiday flag, era notation) and the default behavior. No output schema exists, so the description shoulders the burden of explaining return values, which it does sufficiently. Minor caveat: it does not specify the exact response structure or how 'holiday' is determined, but this is acceptable for a simple tool.

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 documents the date parameter with format and example. The description adds the key semantic that the parameter is optional and defaults to today (Japan time), which is not present in the schema. This goes beyond the 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 returns the weekday (in Japanese), whether the date is a holiday, and the Japanese era notation for a given date. This specific verb+resource combination distinguishes it from sibling tools like jp_list_holidays (list holidays) and jp_convert_era (convert eras).

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 for retrieving detailed information about a single date, but it does not explicitly mention when to use this tool over the sibling alternatives or provide any exclusions. Since there are sibling tools, the lack of explicit differentiation is a gap.

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