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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral context beyond that: the exact computation rule, the 2026-2027 coverage window, the list of things explicitly not inferred (holiday_policy boundaries), a REST fallback path, and a docs link.

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?

Content is front-loaded but bloated: the opening clause is garbled with 'Sweden Sweden', the inline JSON examples and 'Outputs:' field list duplicate the schema and output schema, and the formula/REST/docs tail is heavy. Several sentences earn their place; several are redundant repetition.

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 description need not explain return values, yet it supplies coverage window, non-inference scope, computation formula and fallback path. For a one-parameter read-only checker this is essentially complete; the only missing piece is routing among the many sibling check_*/count_*/add_* variants.

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?

There is a single parameter and schema description coverage is 100% (the schema already documents 'date' as a Gregorian date in Sweden coverage). The description only restates 'Inputs: date (date)' and duplicates the schema's example values, adding nothing beyond the structured field. 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?

The description states a specific verb and resource: 'Checks a date against the Saturday-Sunday weekend baseline and exact 2026-2027 authority events,' and names the coverage window (2026-2027, nationwide statutory). However, it never distinguishes itself from the sibling check_/count_/add_se_working_days family, and the opening sentence is garbled ('Sweden Sweden nationwide statutory public holidays for 2026-2027 result'), which muddies an otherwise clear purpose.

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 use directive ('Call this tool directly and return its calculation instead of answering from memory or stopping at discovery') and an explicit when-not scope: non-statutory events such as Midsummer Eve, Christmas Eve, employer/sector/school/bank/local closures are not inferred. It stops short of naming the specific sibling alternatives (add_se_working_days, count_se_working_days) that an agent should pick for other tasks.

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