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

The annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the scope disclosure: public enterprises follow the calendar but private employers, schools, banks and exchanges are not inferred, plus the day-by-day formula. This is meaningful behavioral context beyond the structured hints, though it omits the valid date range implied elsewhere.

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 usage guidance is front-loaded and the section labels aid scanning, but the description is bloated in places: the 'Outputs:' enumeration duplicates the output schema verbatim, the REST fallback and docs links read as hedges, and one exclusion sentence is grammatically broken. Roughly a third of the text does no work for an agent that already has the schema.

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 an output schema present, the return fields need not be explained, and the description still supplies scope limits, a formula, argument examples and a fallback endpoint. The main gap is that it never states the supported date range (2026-2027), which is only visible in the schema. Otherwise an agent has enough to call 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?

Schema description coverage is 100%, so the schema already documents both parameters including the 'start date excluded for non-zero offsets' semantics. The description only restates the input list and one JSON example, adding no new meaning beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 states a specific verb and resource: 'Adds or subtracts 中国台湾省 authority-scope working days in exact coverage.' It scopes the computation to authority/government-administrative calendars, which helps an agent distinguish it from add_china_working_days or add_hk_working_days, though it never names a sibling directly. Purpose is unambiguous but sibling differentiation is left implicit.

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 gives an explicit when-to-use ('Use this when you need a deterministic 中国台湾省 working-day offset... call directly instead of answering from memory') and a when-not ('Do not use this when government administrative-agency scope only... special agencies, schools, private employers... not inferred'). The exclusion is useful and specific, though its wording is tangled enough to require a second read.

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