Japan MCP Server

MCP for building Japan-native websites with AI.

Local serverstdio

What is the Japan MCP server?

Connect Japan to Claude, Cursor or any other MCP client and it stops being a tab you switch to. MCP for building Japan-native websites with AI. The japan mcp server is what makes that connection.

What the server does

Lead tool: review_jp_ui — the front-end correctness enforcer (run it on any UI, including Western-built, before shipping to Japan).

Available tools

The toolset is worth reading before you wire it up, because it tells you what the integration is really for:

  • review_jp_uiFlagship enforcer — scores CSS/markup against the Japanese UI standard (typography, colour, font payload) with JLReq/JIS citations and fixes
  • generate_jp_form — Outputs Japanese form markup: 姓/名 order, furigana, 〒 postal auto-fill, 3-field phone, 年月日 dates
  • validate_jp_form — Scores a form against JP conventions (0-100) with issues, severity, and code fixes
  • generate_jp_placeholder — Returns test data: names in kanji/katakana/romaji, real postal codes, formatted phone numbers, era dates
  • suggest_keigo_level — Converts English UI text to Japanese at the appropriate politeness level for a given business context
  • score_japan_readiness — Rates a page across five categories: forms, copy, trust signals, typography, cultural fit
  • transform_for_japan — Rewrites Western markup into Japan-ready markup with a before/after score and per-change explanations
  • check_jp_typography — Audits CSS for Japanese typography: font stacks, line-height, kinsoku shori, sizing, palt
  • get_seasonal_context — Returns the current season, active events, 24 microseasons (二十四節気), and launch blackout windows
  • audit_japan_ux — Seven-category audit (layout, typography, visual, navigation, trust, content, mobile) with a letter grade
  • design_direction_for_japan — Produces a Japan-specific design brief from brand type, audience, and industry
  • Typography — The Typography tool exposed by this server

Installation

japan-ux-mcp on npm is all you need. Most clients run it directly, so configuration is a few lines and a restart.

Where it fits

Among the developer tooling options, the useful question is rarely "what can it do" but "what does it cost you to run" — permissions, credentials, and how much of your context its toolset consumes. Japan's toolset — review_jp_ui, generate_jp_form, validate_jp_form and 10 more — is a fair guide to whether it matches your workflow. It is maintained by mrslbt; worth a glance at recent repository activity before you build anything load-bearing on it.

SyncDev reviews every entry in this directory against the project's own documentation before publishing, and revisits them as servers change.

Worth knowing first

  • It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
  • With 13 tools registered it takes up a noticeable share of the context window; turn it off in projects that never touch Japan.
  • Keep per-call confirmation enabled while you learn its behaviour; it is the cheapest safeguard you have.

Available tools

ToolWhat it does
review_jp_ui**Flagship enforcer** — scores CSS/markup against the Japanese UI standard (typography, colour, font payload) with JLReq/JIS citations and fixes.
generate_jp_formOutputs Japanese form markup: 姓/名 order, furigana, 〒 postal auto-fill, 3-field phone, 年月日 dates.
validate_jp_formScores a form against JP conventions (0-100) with issues, severity, and code fixes.
generate_jp_placeholderReturns test data: names in kanji/katakana/romaji, real postal codes, formatted phone numbers, era dates.
suggest_keigo_levelConverts English UI text to Japanese at the appropriate politeness level for a given business context.
score_japan_readinessRates a page across five categories: forms, copy, trust signals, typography, cultural fit.
transform_for_japanRewrites Western markup into Japan-ready markup with a before/after score and per-change explanations.
check_jp_typographyAudits CSS for Japanese typography: font stacks, line-height, kinsoku shori, sizing, palt.
get_seasonal_contextReturns the current season, active events, 24 microseasons (二十四節気), and launch blackout windows.
audit_japan_uxSeven-category audit (layout, typography, visual, navigation, trust, content, mobile) with a letter grade.
design_direction_for_japanProduces a Japan-specific design brief from brand type, audience, and industry.
TypographyThe Typography tool exposed by this server.
SeasonalThe Seasonal tool exposed by this server.

How to install the Japan MCP server

{
  "mcpServers": {
    "japan-ux": {
      "command": "npx",
      "args": ["-y", "japan-ux-mcp"]
    }
  }
}

Add to claude_desktop_config.json, then restart Claude Desktop.

Example prompts to try

  • Use Japan to review jp ui.
  • Use Japan to generate jp form.
  • Use Japan to validate jp form.

Frequently asked questions

It connects Japan to MCP-compatible AI assistants such as Claude and Cursor, exposing 13 tools (review_jp_ui, generate_jp_form, validate_jp_form, and more) that the assistant can call on your behalf. Instead of copying data back and forth by hand, the assistant works with Japan directly.