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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), so the bar is lower. The description adds genuinely non-obvious behavioral rules not present in structured fields: the start date is not counted, and the counting respects holidays, with the Friday/Monday example making the semantics concrete. It does not discuss calendar variants or limits, which the schema covers instead.

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?

Front-loaded with the core operation and backed by one illustrative example; no filler. The bilingual duplication is intentional for a JA/EN tool, so it does not count against conciseness, though it doubles the surface text.

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?

With no output schema, the description carries the return-value burden and does so ('return the date'), plus it explains the counting convention. It stops short of explaining how extra_holidays/extra_business_days interact with the calendar, leaving that to the schema, which is acceptable at 100% coverage.

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 description coverage is 100%, so the baseline is 3. The description's only parameter-relevant content (negative N means before, holidays matter) restates what the schema already says for 'days' and the calendar fields, adding little beyond 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?

States a specific verb and resource ('Return the date that is N business days after/before the given date') and includes a concrete Friday-to-Monday example. It implicitly separates itself from siblings like adjust_to_business_day and count_business_days by describing an offset operation, though it never names or explicitly contrasts them.

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 semantics imply when this tool applies (offsetting a date by N business days), but there is no explicit when-to-use/when-not guidance or mention of the alternative siblings such as adjust_to_business_day or count_business_days. Usage must be inferred from the operation described.

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