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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context about default behavior (default 'from' is today in Japan, default country JP) and the mode switch, but says nothing about ordering, truncation, or how the limit interacts with results.

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 tight sentences that front-load the concept definition before the usage modes. No filler, and the parenthetical definition of 連休 earns its place. Slightly dense but well organized.

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 and no required parameters, the description should carry more of the invocation burden. It covers the core concept and the year/from/country modes adequately, but leaves limit and min_length semantics unexplained, which matters for how many results an agent should expect.

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 only 50%, and the description compensates partially by explaining 'from' (default today), 'year', and the country-driven behavior. But limit and min_length are undocumented in both the schema and the description, so the coverage gap is not fully closed.

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 gives a specific verb ('Find') and resource ('連休 / long weekends'), and it helpfully defines the concept as '3+ consecutive days off made of weekends and national holidays' with concrete examples (Golden Week, Silver Week). It is clear on its own, though it never names or contrasts the sibling tools (list_holidays, business_days, check_dates), so it misses the explicit differentiation that a 5 would require.

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 gives invocation modes ('Give a year, or from (default today) to list upcoming ones') and a country variant, which implies how to use it. However, it never states when to prefer this tool over list_holidays or how the two relate, so guidance is implied rather than explicit.

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