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

Annotations already establish read-only, idempotent, open-world, and non-destructive behavior. The description adds value beyond annotations by naming the Nager.Date data source, the kinds of outputs (yearly list, today flag, upcoming list), and regional holiday coverage, giving the agent a useful behavioral model.

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 four short sentences that front-load the core functionality, then add data source, use cases, and cost. Every sentence contributes useful selection information, with no redundant or filler wording.

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 2-parameter, read-only tool with no output schema, the description covers the query scope and the result categories: yearly holidays, today's status, upcoming holidays, and regional holidays. It does not specify exact return formatting, but the lack of an output schema is mitigated by this behavioral clarity.

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?

The country parameter already has schema-level description with ISO/name examples, and year has min/max bounds. The description adds context about 'any year' and today/upcoming behavior, but it does not explicitly clarify how omitting year changes the query or provide additional parameter-level detail. With 50% schema coverage, this only partially compensates.

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 states a clear resource (public holidays) and specific capabilities: coverage of 100+ countries, any year, today's holiday status, next upcoming holidays, and regional holidays. It is easily distinguished from sibling tools, none of which overlap with holiday data.

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 explicitly names target use cases: 'scheduling, market-closure awareness or delivery estimates.' It does not list alternative tools or exclusions, but no sibling tool directly competes, so the guidance is sufficient for an agent to decide when to call it.

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