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

With no annotations at all, the description carries the full disclosure burden, and it does surface genuinely non-obvious behavior: the tool is paid, at 0.01 USDC on Base via x402, 12 sats Cashu (NUT-24), or 12 sats over Lightning (L402). That payment/auth requirement is exactly the kind of context an agent must know before invoking. It stops short of describing failure modes, rate limits, or what the year parameter defaults to.

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 sentences, zero filler. The functional scope and the country-code format lead, and the payment mechanics follow; every clause adds information an agent cannot get from the bare schema.

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?

For a simple two-parameter lookup with no output schema and no annotations, the description covers the return content (dates, local names, regions), the data source, the country format, and the payment requirement. The remaining gap is the optional-year default and the response shape, which the absent output schema would otherwise have had to carry.

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 description coverage is 0%, so the description has to compensate, and it does for both parameters: country is specified as an ISO code with concrete examples (AU, US, GB), and year is identified as the year of interest. It does not state the accepted year format or that year is optional and what happens if it is omitted, leaving a small but real gap.

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 names the exact resource (public holidays), the scoping axes (country and year), and what the response contains (dates, local names, regions) plus the upstream source (Nager.Date). No sibling tool covers holidays, so an agent can route to it unambiguously from the name-plus-description alone.

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: the description says it returns holidays for a country/year, from which an agent infers when to call it. There is no explicit when-to-use statement, no mention of what to do when the year is omitted, and no named alternative or exclusion.

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