I18n

What i18n does

The i18n MCP server exposes internationalization and localization operations to AI agents through MCP. It can inspect text to identify a likely language and BCP 47 locale, including the writing system, confidence value, and alternative candidates. Detection supports English, Spanish, French, German, Portuguese, Italian, Russian, Japanese, Korean, Chinese, Arabic, Hindi, Thai, Greek, and Hebrew.

The server also helps prepare and review application translations. It can find user-facing strings in JSX or TSX attributes, HTML templates, logging calls, thrown errors, browser dialogs, and variables whose names suggest user-facing content. For each result, it reports source location, nearby context, the matched pattern, and a proposed key.

How it works

An MCP-compatible client starts the compiled Node.js entry point as a stdio server. The client sends tool calls for the requested localization task and receives structured results. The i18n MCP server does not require a separate hosted service in the documented setup.

Translation analysis compares locale JSON files against a reference locale. It reports missing and unexpected keys, differences in value shape, inconsistent interpolation placeholders, blank values, and optionally keys that are not used in source code. Plural evaluation follows CLDR categories and can classify supplied test numbers for a locale.

Formatting uses the JavaScript Intl APIs. Number operations cover decimal, percentage, unit, compact, scientific, and engineering notation. Currency output can use symbols, narrow symbols, currency codes, or currency names. Date formatting offers short, medium, long, and full styles, with date-part details; relative time supports long, short, and narrow styles with automatic numeric wording.

Setup and configuration

Install dependencies and build the project from its repository:

npm install
npm run build

Configure the MCP client to run Node against the generated entry point. The documented configuration uses a command of node and an argument pointing to dist/index.js; adjust the path for the local checkout.

{
  "mcpServers": {
    "i18n-tools": {
      "command": "node",
      "args": ["/path/to/mcp-i18n-tools/dist/index.js"]
    }
  }
}

No environment variables or remote credentials are specified in the provided setup instructions.

Tools and capabilities

• detect_locale identifies a language and locale from text and returns confidence and alternatives.
• extract_i18n_keys locates hardcoded strings that may need internationalization and suggests keys.
• analyze_translations compares locale JSON structures and values, including interpolation placeholders.
• plural_rules lists CLDR plural categories and classifies supplied numbers.
• format_locale formats numbers, currencies, dates, and relative times for a selected locale.

The i18n MCP server is suited to code review and localization maintenance, but the documented tools do not describe translation generation or a translation-provider connection. Translation analysis can identify inconsistencies; it does not imply that missing text is automatically translated.

Limitations and notes

Locale detection is limited to the languages listed in the project documentation. Unused-key checks require the caller to provide a list of keys used in source code. Translation comparison is described for JSON locale files. The server is distributed under the MIT license.