主要市場の取引時間ステータス

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

Despite no annotations, the description provides detailed behavioral information: market-specific hours, status values, handling of weekends and holidays, manual curation of holidays, and limitations regarding daylight saving time and unscheduled closures. This is highly transparent.

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, well-structured, front-loading the core functionality (markets and status types) and then adding details about holidays and limitations. No wasted words.

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 has no parameters or output schema, but the description fully explains what it returns (status with market-specific times, holiday names) and covers important edge cases (weekends, manual curation, daylight saving gap). It is complete for a simple status 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?

There are no parameters (0 params, schema coverage 100%). The description adds value by explaining the output context, which is sufficient given no parameters need documentation.

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 current trading session status (open/pre-open/closed/holiday) for four major markets with specific times. It distinguishes itself from sibling tools by focusing solely on market session status, not on calculations or quotes.

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 checking market sessions but does not explicitly state when to use this tool vs alternatives or when not to use it. However, sibling tools are clearly different in purpose.

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