営業日数カウント

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

The description discloses the inclusive endpoint behavior, which is a key behavioral trait. However, it does not mention how weekendDays and customHolidays affect the count, default weekend behavior, or edge cases like reversed dates. With no annotations provided, the description carries the burden but leaves these details to the schema.

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 a single, concise sentence that front-loads the primary action and scope. Every word contributes to understanding the tool's purpose with no redundancy or filler.

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 simple counting tool with a rich schema (75% parameter coverage), the description adequately covers the core functionality and inclusivity. It does not explain edge cases, but the schema and the tool's straightforward nature make it sufficiently complete for an agent to select and invoke it correctly.

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 description clarifies that both startDate and endDate are included in the count, which adds meaning beyond the schema's basic date string descriptions. Since schema coverage is 75% (endDate lacks a direct description), this compensation is valuable. The other parameters (weekendDays, customHolidays) are already well-described in 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 uses a specific verb '数えます' (counts) and clearly identifies the resource: '2つの日付の間' (between two dates) of business days. It also specifies inclusivity with '(両端を含む)' which distinguishes it from sibling tools like is_business_day (single date check) and add_business_days (adding days).

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 the usage scenario (counting business days between dates) but does not explicitly mention when to use this tool over alternatives like is_business_day or add_business_days. There are no exclusions or prerequisites stated, so the guidance is adequate but not fully explicit.

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