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

No annotations are provided, so the description carries the full behavioral burden. It never states whether weekends and Japanese public holidays are excluded, what date format is expected, whether negative values are supported (only implied by 'add/subtract'), or what the response contains. 'Japanese business days' is the only real behavioral signal.

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?

Two short sentences, front-loaded with the action and domain. The 'PRO.' prefix is trivial overhead but the rest is efficient with no 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?

A mutation-free but computation-heavy tool with no annotations, no output schema, and two of three parameters undocumented. The description should explain the holiday calendar semantics, date input format, and negative-day behavior, and it explains none of these.

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 coverage is only 33% (only access_token is documented in the schema). The description implies 'days' can be negative and 'start' is a date, but gives no format, range, or sign conventions, and never mentions the required access_token. It does not compensate for the low coverage.

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?

States a specific verb (add/subtract) and a specific resource (Japanese business days) applied to a date. It is clear on its own, though it never names or contrasts with siblings like next_holidays or due_date, so differentiation is left to inference.

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?

There is no when-to-use or when-not-to-use guidance and no pointer to alternatives such as due_date or year_planner. The 'PRO' prefix conveys nothing actionable about selection.

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