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

With no annotations, the description must carry the load, and it does disclose two invocation-critical facts: the $0.01 USDC-on-Base charge and that payment goes in params._meta["x402/payment"]. It does not state that the call is read-only, what the response contains, or any rate-limit/failure behavior.

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 with the calendar concept, but the pricing is stated twice almost verbatim ('$0.01 per call in USDC on Base via x402' then 'Price: $0.01 per call in USDC on Base (eip155:8453)'), wasting roughly a third of the text on a duplicate.

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?

Payment and endpoint information are present, but with no output schema the description never says what a 'list a year's holidays' response looks like (array of dates? names?), and it never disambiguates this tool from its four siblings. Adequate but with clear gaps for a 3-required-parameter call.

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% with formats and an enum, so the schema already fully documents country/start/end. The description adds nothing about parameter semantics beyond restating US/UK scope, which the country enum description already covers — 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 opening states a resource ('Public holiday and business-day calendar for US and UK') but then lists four distinct operations — day check, add N days, count between, list a year's holidays — only the last of which is this tool. With siblings bizcal_api__day, add, between, and workdays present, the shared capability list makes it impossible to tell from the text alone which operation 'year' performs.

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 when-to-use guidance and no routing to alternatives, even though four sibling tools cover the other listed capabilities. The only actionable instruction is payment mechanics, not selection guidance.

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