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

With no annotations, the description carries the full burden and does disclose two behaviors an agent needs: cost (0.001 USDC per call via x402) and the content of the response. It does not summarize the two-step 402 handshake or state whether a year must be supplied, leaving that to the schema.

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 padding, with the core scope front-loaded and the cost deferred to the end where it belongs.

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 read-only lookup with no output schema, listing the returned fields and the price makes this largely complete. The remaining gap is the optionality/default of year and any mention of the payment retry flow, though the latter is covered by the paymentProof schema description.

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 67%: country and paymentProof are well documented in the schema, but year has only min/max bounds and no meaning. The description repeats 'ISO code' and 'year' without clarifying that year is optional or what the default is, so it adds little beyond the schema.

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?

States a specific verb+resource (retrieve official public holidays) scoped by country ISO code and year, and even names the return shape: local names, nationwide flag, next upcoming holiday. No sibling in the catalog overlaps with holiday lookup, so no disambiguation is needed.

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?

The purpose makes the use case implicit (holiday lookups for a given country/year), and the pricing note hints at cost-sensitive calls, but there is no explicit when-to-use/when-not guidance or pointer to a complementary tool (e.g. geocode for resolving country names to ISO codes).

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