Japan & World Public Holidays

by omikuji.dev · remote · no sign-in to list tools · v1.1.0 · published by dev.omikuji

Public holidays, business days and long weekends for Japan (Cabinet Office) and 245 other countries.

Changes · 1

Compare Registry entry

4 tools: 1 change things and 3 only read.

Scanned Oct 21, 2026

Deletes or cancels0Claude Code: deny
Can't be undone0Claude Code: ask
Changes things1Claude Code: ask: see these tools
Only reads3Claude Code: allow: see these tools

No check matched anything in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http holiday https://holiday.omikuji.dev/mcp

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

4 tools

Changes things 1Creates or changes something that can be changed back.Claude Code: ask

check_datesFor 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.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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).
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
- title: Check dates

Only reads 3Looks things up and changes nothing.Claude Code: allow

business_daysCount business days between start and end (inclusive), or find the date that is N business days after start (add=N; negative N goes backward; start itself is not counted).No findings
Why it is in this group
- The description's first verb is "count": a word for reading.
Description, as the server wrote it
Count business days between start and end (inclusive), or find the date that is N business days after start (add=N; negative N goes backward; start itself is not counted). Business day = weekday that is not a national holiday. Set year_end_closed to also skip 12/29-1/3. With country, uses that country's weekend days, holidays and make-up workdays.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
- title: Business days
find_long_weekendsFind 連休 (3+ consecutive days off made of weekends and national holidays), e.g.No findings
Why it is in this group
- The name "find_long_weekends" says "find": a word for reading.
Description, as the server wrote it
Find 連休 (3+ consecutive days off made of weekends and national holidays), e.g. Golden Week, Silver Week. Give a year, or from (default today) to list upcoming ones. With country, the same for that country.
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
- title: Find long weekends
list_holidaysList Japanese national holidays for a year, or between from and to.No findings
Why it is in this group
- The name "list_holidays" says "list": a word for reading.
Description, as the server wrote it
List Japanese national holidays for a year, or between from and to. With no arguments, lists the next 10 holidays from today (Japan time). With country, lists that country's public holidays (and make-up workdays, if any).
Annotations the server declares
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
- title: List holidays

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Exfil surface

Which tools read private data, which read text someone else can write, and which can send data out. One of each is a path a prompt injection can use.

No private-data, untrusted-input, outbound path in this server alone: no tool is tagged private-data or untrusted-input or outbound.

Reads private data0: Reads files, mail, messages, databases, secrets, calendars or repositories.
Reads text others write0: Brings in text someone else can write: web pages, inbound email, messages, issues and comments.
Can send data out0: Can carry data to people or systems: it sends, posts or publishes, or takes a recipient, channel or URL.

Other servers in the same agent add their own tools to these paths. Audit your whole setup to see them together.

Remote posture

What anyone on the internet sees at the remote endpoint: an anonymous initialize and tools/list, and the public OAuth metadata.

Looked at Oct 22, 2026, 15:17 UTC, unchanged since Oct 22, 2026. No credentials were sent and no tool was called. What is looked at.

Reachable: yes
HTTP status of an anonymous initialize: 200
tools/list served without credentials: yes
Tools that change things, listed without credentials: 1
Protocol version: 2025-06-18
WWW-Authenticate on 401: not observed
resource_metadata in WWW-Authenticate: none
RFC 9728 protected resource metadata: none
Authorization servers: none
Legacy HTTP+SSE transport: no
Dynamic client registration: not observed
Client ID metadata documents: not observed

WarnThe whole server
The endpoint served tools/list without credentials, and the list has 1 tool that changes things (1 write). Whether a call also works without credentials was not tested: tools are never called.
Matched text
https://holiday.omikuji.dev/mcp: tools/list returned 4 tools to an anonymous client, including check_dates (write)
What this check looks for

Install

Pinned to version 1.1.0. Values in angle brackets are yours to fill in.

claude mcp add --transport http holiday https://holiday.omikuji.dev/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change or a way out, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json

{
  "permissions": {
    "allow": [
      "mcp__holiday__list_holidays",
      "mcp__holiday__business_days",
      "mcp__holiday__find_long_weekends"
    ],
    "ask": [
      "mcp__holiday__check_dates"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. A read that can send data out (it takes a URL, say) asks first too. It assumes the server is installed as holiday. Review it before you use it.

Keep track

Get told when this server's tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/dev.omikuji/holiday/changes.xml

An Atom feed. Works in any feed reader or Slack's RSS app.

Anlyon alternative

1 of these tools change something. Run those as governed actions.

Declare what an action changes, and Anlyon puts it under a shared limit, binds every approval to the exact request, and grades the outcome. It works on any HTTPS API you can describe as an action.

Anlyon does not run, proxy or govern this MCP server. A tool your own code calls directly is not routed through Anlyon and is not governed by it.

Import an OpenAPI spec →

Compare with other servers for the same product.

Source: MCP Registry. Synced Oct 21, 2026, 18:11 UTC.

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