Public holidays

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

Annotations only declare readOnly/idempotent/closed-world; the description adds material behavior they cannot convey: lunar and government-proclaimed dates are rule-based estimates (a data-quality caveat that changes how results should be trusted), and the cost model of 25 free calls per day then $0.001/call via x402. Pricing and reliability caveats are exactly the kind of context an agent needs before calling.

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?

Three dense sentences: capability and scope first, use cases second, caveats and pricing last. No filler, and every clause (country count, year range, estimate caveat, free tier) carries information an agent would otherwise have to discover by trial.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. The description fills the remaining gaps a two-parameter lookup tool has: data reliability for movable holidays and the per-call cost after the free tier.

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 100%, with both parameters documented including the default year and the ISO alpha-2 pattern. The description repeats the 207-country and 2000–2050 bounds already in the schema and adds only the note that a country's holidays are excluded from business days, so it does not meaningfully extend parameter meaning.

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 and resource ('List public holidays') plus synonyms (bank holidays, national holidays), scope dimensions (country, year), and hard coverage limits (207 countries, 2000–2050). An agent can tell this apart from calendar-math siblings like date_add or business_day without opening the schema.

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?

Gives concrete use cases ('holiday calendars, office closures and checking if a date is a holiday'), which frames when to reach for it. It does not name any alternative tool or state exclusions, so the overlap with business_day (which excludes holidays) is left implicit.

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