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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered; the description still adds real behavioral context: the coverage window is limited to 2026-2027, Saturdays are treated separately from Sundays/holidays, and the declared Monday-Friday business baseline excludes Eves and local/collective closures. It also discloses the exact formula and a REST fallback endpoint, which is unusually transparent.

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?

Usage guidance and caveats are front-loaded, which is good, but the text is bloated: a duplicated 'Norway Norway', a broken conditional clause, and a full REST fallback URL plus docs link and formula that many callers won't need. Most sentences earn their place, but the garbled openings and duplication cost it.

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?

An output schema exists, so enumerating outputs is redundant, but the description still covers the critical dimensions an agent needs: the 2026-2027 coverage limit, the weekend baseline definition, and what holiday categories are deliberately excluded. Given the low complexity and rich schema/annotations, this is close to complete.

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?

With a single parameter at 100% schema description coverage, the schema already carries the semantics ('Gregorian date in Norway coverage'). The description restates 'Inputs: date (date)' and adds two concrete JSON examples, but contributes little beyond the schema's own format and examples, so this sits at the baseline.

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 concrete verb+resource: it 'Checks a date against the Saturday-Sunday weekend baseline and exact 2026-2027 authority events' for Norway, producing an is_working_day result. The Norway scope and 2026-2027 window differentiate it from the many sibling check_*/add_* country tools. However, the opening sentence is garbled ('Norway Norway nationwide statutory public holidays for 2026-2027 result'), which muddies first-read clarity.

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 explicit positive guidance ('Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery') and negative scope ('Do not use this when nationwide statutory full-day list only'), and lists what is not inferred (Eves, collective-agreement, sector, school, bank, local closures). The 'Do not use this when...' clause is syntactically broken but the exclusions themselves are actionable.

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