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

No annotations are provided, so the description carries the full behavioral burden. It establishes that this is a read operation returning a list and scopes the data to Japanese holidays only, which is useful context, but says nothing about error handling for contradictory inputs, out-of-range years, or result ordering.

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: the purpose statement is front-loaded, followed immediately by concrete call examples. No filler, though the examples mildly duplicate the schema's own parameter documentation.

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 three-parameter read-only lookup with no output schema and full schema coverage, the description is largely sufficient. The only minor gap is that the year/from-to mutual exclusivity is left to the schema rather than restated, but nothing an agent needs to select or invoke the tool is missing.

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%, so the schema already documents each parameter's format and the year vs. from/to mutual exclusivity. The description's inline examples illustrate valid combinations but add no format or syntax detail beyond what the schema provides. Baseline 3 is appropriate.

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 ("日本の祝日一覧を返します" – returns a list of Japanese holidays) with clear scope (year or date range). It is easy to distinguish from siblings like is_holiday or add_business_days, though it never names those alternatives. Clear but not fully sibling-differentiating.

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 two input examples imply the two supported modes (single year vs. date range), giving implied usage guidance. However, there is no explicit statement of when to prefer this over is_holiday or business_days_between, and no exclusion conditions beyond what the schema already encodes.

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