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

With no annotations, the description carries the full burden and delivers: counting starts the day after the given date, negative days go backward, weekends and Japanese holidays are excluded, the 'banking' calendar adds bank holidays, and days=0 behavior is explained with the skipped field. This is comprehensive behavioral disclosure.

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 compact yet information-dense, front-loading the core operation, then covering edge cases, calendar options, an alternative tool, and an example—all without unnecessary 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?

Given that there is no output schema, the description explains the result and mentions the skipped field, but the exact return structure (e.g., whether it's a plain date string or an object with metadata) is not fully specified. It covers negative days, zero days, calendar variants, and alternatives, so it is quite complete overall.

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 100%, so the baseline is 3. The description adds meaning beyond the schema: the starting date is not counted, negative days indicate backward calculation, calendar options are explained, and days=0 semantics are clarified. It doesn't add new meaning for extra_closed_dates, but the schema already documents it.

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's function: returning the date that is N business days after or before a specified date, with explicit counting rules. It distinguishes from the sibling is_holiday by directing users to that tool for simple business-day checks.

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?

It explicitly says to use is_holiday if only checking whether a date is a business day, and notes that days=0 can also provide that via skipped. However, it does not mention business_days_between or list_holidays, so sibling differentiation is not complete.

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