LexiLint MCP

Spell and grammar checking for AI assistants via Model Context Protocol (MCP).

Works with Claude Desktop, Cursor, ChatGPT, and other MCP-compatible clients.

Features

• Offline spell checking — en-US and en-GB are free, local, unlimited, and make no API calls.

• BYOK grammar checking — use Gemini, OpenAI, or Anthropic with your own provider key.

• Eight supported dictionaries — two free English variants plus six Premium languages: Spanish, French, German, Polish, Russian, and Turkish.

• Combined checking — run spelling and optional grammar together with check_text.

• Private provider transport — grammar text goes directly to the selected provider; LexiLint does not proxy it.

Related MCP server: i18n Agent

Install and configure

Claude Desktop and other JSON-configured clients

Configure one provider key as an environment variable. This keeps the key out of tool calls and conversation context.

{
  "mcpServers": {
    "lexilint": {
      "command": "npx",
      "args": ["-y", "lexilint-mcp"],
      "env": {
        "GEMINI_API_KEY": "your-gemini-api-key"
      }
    }
  }
}

Provider environment variables:

Common Claude Desktop config locations:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

• Windows: %APPDATA%\Claude\claude_desktop_config.json

Restart the client after changing its MCP configuration.

Run directly

npx -y lexilint-mcp

You can also install it globally with npm install -g lexilint-mcp.

Tools

spell_check — free and offline

Checks spelling without an API key or network request.

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

grammar_check — BYOK grammar, style, and clarity

text        string   Text to grammar-check
provider    string   "gemini" | "openai" | "anthropic"
api_key     string   Optional per-call override for the provider environment variable
model       string   Optional provider model ID (Premium when custom)
license_key string   LexiLint licence key for Premium providers/languages/models
language    string   Language code (default: "en-US")

With GEMINI_API_KEY configured, a client can call the tool without putting the provider key in its arguments:

{
  "text": "This are a test.",
  "provider": "gemini",
  "language": "en-US"
}

A non-empty per-call api_key remains supported as an explicit override and takes precedence over the selected provider environment variable:

{
  "text": "This are a test.",
  "provider": "gemini",
  "api_key": "temporary-override-key",
  "language": "en-US"
}

Get a free Gemini key from Google AI Studio. Do not paste real keys into chat messages; prefer your MCP client's local environment configuration.

check_text — combined spelling and optional grammar

Always runs the available spelling check. Add provider to request grammar; omit it to skip grammar without requiring a provider key.

text        string   Text to check
language    string   Language code (default: "en-US")
provider    string   Optional; omit to skip grammar
api_key     string   Optional per-call override for the provider environment variable
model       string   Optional provider model ID (Premium when custom)
license_key string   LexiLint licence key for Premium providers/languages/models

Models and Premium access

Default models are gemini-3.8-flash, gpt-5.6-terra, and claude-sonnet-5. A custom model requires LexiLint Premium:

{
  "text": "This are a test.",
  "provider": "gemini",
  "model": "gemini-3.7-flash",
  "license_key": "your-lexilint-license-key"
}

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

Customers provide only their provider key and, for Premium features, their LexiLint licence key. The runtime already contains the public application configuration needed to validate a licence with Polar; customers do not configure a LexiLint signing secret or organisation ID.

Privacy and repository boundary

• Spell checking is local and sends no text anywhere.

• Grammar text goes directly to Google, OpenAI, or Anthropic according to the provider you select.

• LexiLint does not receive provider keys or grammar text.

• The public raunakkathuria/lexilint-mcp repository is a metadata-only registry mirror containing exactly LICENSE, README.md, glama.json, and server.json. Private source, builds, tests, source maps, and standalone prompt documentation are not published there.

Links

• npm package

• Website and docs

• Chrome Extension

• MCP Registry

Licence

LexiLint MCP is proprietary software distributed under the terms in LICENSE. Installing the package does not open-source the private monorepo or grant redistribution rights.