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

Annotations already cover read-only, idempotent, and closed-world traits, so the bar is lower. The description adds genuine behavioral context beyond the annotations by specifying that mode=bank treats midsommarafton, julafton, and nyårsafton as non-business days, though it does not clarify what mode=work does differently.

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?

Two dense sentences with zero filler: the first lists the returned information, the second front-loads the key mode behavior. Every phrase earns its place and the critical mode detail follows immediately.

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 usefully names the return fields (weekday sv/en, ISO week, holiday names, business-day status), and annotations cover the safety profile. Minor gaps remain, such as which holiday set is used and the work-mode default behavior, but nothing essential to invoking it 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 coverage is 100%, making 3 the baseline, but the description earns extra credit by defining what the bank enum value means operationally (specific eve days treated as non-business). It adds meaning beyond the schema's bare 'bank or work' and 'YYYY-MM-DD' descriptions.

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 enumerates the concrete outputs (weekday in sv/en, ISO week, holiday names, business-day status) for a date, which is a specific verb-resource statement. It does not explicitly differentiate itself from siblings like swedish_holidays, add_business_days, or count_business_days, so it falls short of a 5.

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?

There is no explicit guidance on when to use this tool versus the many sibling date tools (swedish_holidays, add_business_days, count_business_days). The mode=bank explanation implies its business-day context but does not route the agent between alternatives or state exclusions.

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