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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, but the description adds real behavioral context: the 2026-2027 scope limit, state-level (non-local/employer) calendar semantics, the counting formula, and a REST fallback with a warning not to guess other /api/* paths. That goes meaningfully beyond the structured annotations.

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 well, with when-to-use and when-not-to-use leading, but it then enumerates the full output field list (start_date, result_date, ..., dataset_version) which duplicates the existing output schema and bloats the definition. The many labeled sections make it scannable but not tight.

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 an output schema exists, the description need not explain return values, and it still supplies scope limits, formula, example arguments, fallback endpoint, and docs link. Nothing an agent needs to call this correctly is missing.

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 start_date, division enum, and the signed working_days offset. The description restates the inputs and repeats a JSON example without adding syntax or constraint detail beyond the schema, so the baseline 3 applies.

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: 'Adds or subtracts working days using the selected Australian state/territory public-holiday calendar,' which separates it from the check_/count_australia_* siblings by the additive behavior. It does not explicitly name those siblings, so differentiation is implied rather than stated.

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?

Gives an explicit when-to-use ('a state/territory-specific Australian date offset in 2026-2027'), an explicit when-not-to-use ('division unknown or the task needs local, employer, exchange or future-year rules'), and instructs the agent to return the calculation rather than compute from memory. It stops short of naming the alternative sibling tools for the excluded cases.

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