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

Annotations cover only the safety profile (readOnly, idempotent, openWorld), and the description adds the operational facts an agent actually needs: it is a paid tool, priced at $0.001 per successful call via x402 USDC on Base, and an unpaid call returns a PaymentRequired object. It also discloses the typical result window (remainder of the year into the next), which is behavior no annotation conveys.

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?

The use case is front-loaded and the payment caveat is appended compactly in one sentence. The sentence is long and packs example query, source, limit, and billing together, but every clause carries information an agent needs.

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?

With no output schema, the description carries the burden of describing returns, and it does so at a high level (upcoming holidays from today, typically through the next year). The billing/payment flow is fully covered; only the concrete shape of the returned holiday records is left implicit.

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 country (ISO 3166-1 alpha-2) and limit (1-50) documented in the schema itself, so the baseline is 3. The description only restates that limit 'caps the list' and adds no format or edge-case detail 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 and resource (returns the next public holidays for a country) and pins the temporal scope to 'from today', which separates it from the year-scoped siblings holidays and holiday_check. The upstream source (Nager.Date NextPublicHolidays) is named, so the agent knows exactly what data it gets.

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?

Opens with an explicit use case ('Use to answer "when is the next public holiday in Germany?"'), giving clear context for when to reach for it. It does not name alternatives such as holidays or holiday_check or state exclusions, so it stops short of full when/when-not routing.

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