Japan Public Holidays

Check dates

check_dates

Read-onlyIdempotent

For each date, tell whether it is a Japanese national holiday (with name and kind: 祝日 / 振替休日 / 国民の休日), a weekend, and a business day. Also returns today in Japan time. With country, the same for that country (holiday names, status, make-up workdays such as China's 调休).

Input Schema

TableJSON Schema

Name	Required	Description	Default
`dates`	Yes
`region`	No	Outside Japan: state/province code (ISO 3166-2 suffix, e.g. CA for California) to include regional holidays.
`country`	No	ISO 3166-1 alpha-2 country code (e.g. JP, US, CN, GB). Default JP.	JP
`year_end_closed`	No	Japan only: treat 12/29-1/3 as non-business days (common in Japanese companies).

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedOct 15, 2026

addedInput schema / properties / country

Added value: +{
+  "default": "JP",
+  "description": "ISO 3166-1 alpha-2 country code (e.g. JP, US, CN, GB). Default JP.",
+  "pattern": "^[A-Za-z]{2}$",
+  "type": "string"
+}

addedInput schema / properties / region

Added value: +{
+  "description": "Outside Japan: state/province code (ISO 3166-2 suffix, e.g. CA for California) to include regional holidays.",
+  "type": "string"
+}

changedInput schema / properties / year_end_closed / description

Previous value: -"Treat 12/29-1/3 as non-business days (common in Japanese companies)."New value: +"Japan only: treat 12/29-1/3 as non-business days (common in Japanese companies)."

First observedOct 15, 2026

TDQS

A3.7/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description usefully adds behavioral context beyond that: it returns today in Japan time, classifies holidays into 祝日/振替休日/国民の休日, and notes make-up workdays (调休) for other countries.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two dense sentences with the primary behavior (per-date classification plus today in Japan) front-loaded and the country extension second. No filler, though the parenthetical lists of holiday kinds add moderate length.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

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 explaining returns and does so for the main path (holiday name/kind, weekend, business day, today in JP time, country behavior). It stops short of describing the region parameter's effect, a minor gap against a 4-parameter tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 75%, so the schema already documents the parameters well, and the description only reinforces the country-switching behavior. It adds no detail on region (ISO 3166-2 suffix) or year_end_closed, leaving those entirely to the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Names a specific verb (tell whether) and resource (dates), and enumerates exactly what it reports: holiday status with kind, weekend, business day. It is distinguishable in substance from list_holidays and business_days, though it never names those siblings to draw the boundary explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied by the enumeration of outputs (checking one or more dates for holiday/weekend/business-day status), but there is no explicit when-to-use statement, no when-not, and no pointer to the sibling tools it overlaps with (list_holidays, business_days).

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

All Japan Public Holidays tools Inspect

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