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

Annotations already declare readOnlyHint and openWorldHint, so the description earns credit for adding what they cannot: a paid call costing $0.002 USDC on Base via x402, which is material to an agent deciding whether to invoke. It still omits failure behavior (unknown ISO code, unsupported year) and whether results are cached or deterministic.

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 short sentences, front-loaded with the capability and followed by the payment precondition. Nothing is padded, though the cost note could be phrased more tightly.

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?

No output schema exists, and the description does hint at the payload contents (holiday list, weekend definition, make-up workdays), which is enough for an agent to know what it gets back. A brief note on the result shape or on error cases for bad country/year would close the remaining gap.

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% and both parameters are documented in-schema (year as YYYY, country as ISO alpha-2), so baseline is 3. The description merely restates 'country and year' and adds no format or edge-case detail (e.g., case sensitivity of the country code, year boundaries).

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 resource and scope: national public holidays for a country and year, plus weekend definition and make-up workdays. It is clearly distinguishable in practice from the business-day arithmetic siblings, but it never names them or states the distinction explicitly.

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?

Usage is only implied by the resource ('holidays' vs. business day math). There is no explicit when-to-use / when-not statement, no note about which sibling to pick for counting business days versus listing holidays, and no guidance on valid country codes or year ranges.

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