LexiLint MCP Server

Spell and grammar checking for AI assistants (Claude, ChatGPT, Cursor, etc.) via the Model Context Protocol.

Free: Spell check — 100% offline, no API key, no data leaves your machine. Premium: Grammar check — uses your own API key (BYOK). Google Gemini has a free tier.

Install

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "lexilint": {
      "command": "npx",
      "args": ["lexilint-mcp"]
    }
  }
}

Config file location:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

Other MCP clients

npx lexilint-mcp

Tools

spell_check — Free, 100% offline

Check text for spelling errors. No API key needed. Supports en-US and en-GB.

Input:
  text      string   Text to spell-check
  language  string   "en-US" or "en-GB" (default: "en-US")

Output:
  List of spelling errors with word, offset, and suggestions

grammar_check — Requires API key (BYOK)

Check text for grammar, style, and clarity issues using your own AI provider.

Input:
  text      string   Text to grammar-check
  provider  string   "gemini" | "openai" | "anthropic"
  api_key   string   Your API key for the selected provider
  language  string   Language code, e.g. "en-US", "fr", "de" (default: "en-US")

Output:
  List of issues with type, severity, original text, and suggestion

Getting a free Gemini API key:

1. Go to aistudio.google.com
2. Click "Get API key"
3. No credit card required

check_text — Combined (spell always free, grammar optional)

Run spell check and optionally grammar check in one call.

Input:
  text      string   Text to check
  language  string   Language code (default: "en-US")
  provider  string   Optional — omit to skip grammar check
  api_key   string   Required if provider is set

Output:
  Spell check results + grammar results (if provider/api_key provided)

Privacy

• Spell check: 100% local. Zero network requests. Your text never leaves your machine.
• Grammar check: Your text goes directly from your machine to your chosen AI provider (Google, OpenAI, or Anthropic). LexiLint never sees it. This is BYOK — you authenticate with your own key.

Free vs Premium

| Feature | Free | Premium ($2.99/mo or $29.99 lifetime) | |---|---|---| | Spell check (en-US, en-GB) | ✅ Offline, unlimited | ✅ | | Grammar check with Gemini | ✅ BYOK — free key at aistudio.google.com | ✅ | | Multi-language spell check | ❌ | ✅ es, fr, de, ru, pl, tr | | Multi-language grammar | ❌ | ✅ | | OpenAI GPT-4 grammar | ❌ | ✅ BYOK | | Anthropic Claude grammar | ❌ | ✅ BYOK | | Custom AI model selection | ❌ | ✅ |

Get Premium: https://igniteapp.net/lexilint#premium

Also available as a Chrome Extension

LexiLint for Chrome — check spelling and grammar on any webpage, including localhost and staging sites.