xcstrings-mcp

MCP server for iOS/macOS .xcstrings localization file management.

The Problem

Xcode String Catalogs (.xcstrings) are large JSON files that waste LLM context windows when loaded whole. Manual editing risks corrupting Xcode's specific formatting, there's no validation for format specifiers or plural rules, and plural-aware translation requires understanding CLDR categories across 40+ locales.

Quick Start

Install

cargo install xcstrings-mcp
# or
cargo binstall xcstrings-mcp

Configure Claude Code

claude mcp add xcstrings-mcp -- xcstrings-mcp

Usage

Typical workflow:

Parse the .xcstrings file to cache it
Get untranslated strings in batches that fit the context window
Submit translations with automatic validation and atomic writes

parse_xcstrings → get_untranslated → submit_translations

Tools

Tool	Description
`parse_xcstrings`	Parse and cache `.xcstrings` file
`get_untranslated`	Get untranslated strings with batching
`submit_translations`	Validate and write translations atomically
`get_coverage`	Per-locale coverage statistics
`get_stale`	Find stale/removed keys
`validate_translations`	File-wide validation report
`list_locales`	List locales with stats
`add_locale`	Add new locale with empty translations
`get_plurals`	Extract keys needing plural translation
`get_context`	Find related keys by shared prefix

Architecture

┌─────────────┐    stdio/JSON-RPC    ┌─────────────────┐    File I/O    ┌──────────────────────┐
│ Claude Code  │◄───────────────────►│  xcstrings-mcp   │◄────────────►│ Localizable.xcstrings │
│ (translates) │                     │ (Rust MCP server)│              │ (JSON on disk)        │
└─────────────┘                     └─────────────────┘              └──────────────────────┘

Layered architecture: server -> tools -> service -> model, with io injected via the FileStore trait.

server -- MCP tool routing and handler dispatch
tools -- individual tool implementations
service -- pure logic (parser, extractor, merger, validator, formatter); no I/O
model -- serde types for .xcstrings format, CLDR plural rules, format specifiers
io -- FileStore trait + real filesystem implementation with atomic writes

License

Licensed under either of

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

See CONTRIBUTING.md for development setup and guidelines.

xcstrings-mcp 0.3.2