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

Annotations already mark the operation as read-only, idempotent, open-world, and non-destructive. The description adds useful extra behavioral context: the third-party source (Nager.Date), the per-call cost, and the HTTP endpoint. This goes beyond the annotations without contradicting them.

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 description is short and front-loaded with the core purpose, followed by source, cost, and endpoint. One minor redundancy exists: 'Public holidays' appears in both the title and the first phrase. Overall, it wastes very few words and is easy to parse.

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 two well-documented parameters, the description provides enough context to select and invoke the tool: what it returns, for which country/year, and at what cost. There is no output schema, but the description sufficiently conveys the expected result type. It could add a brief statement about the response shape or holiday names/dates, but this is a minor gap.

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 both parameters (country and year) described with examples. The description only repeats that the tool uses country and year, adding no new meaning beyond the schema. The baseline of 3 is appropriate because the schema already carries the semantic weight.

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 clearly identifies the tool as returning public holidays for a given country and year. It names the resource (public holidays), scope (country & year), and source (Nager.Date), making the tool understandable. It does not use an explicit verb like 'get' or 'list,' but the intent is unambiguous.

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 description states that this tool is for retrieving public holidays filtered by country and year, which gives clear context for when to call it. It does not explicitly mention alternatives or exclusion cases, such as comparing with v1_business_days, but the usage context is reasonably clear.

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