AI Security Gateway — MCP Server

Local PII detection and masking for Claude Desktop, Cursor, and Windsurf. Your prompts are scanned on your machine before reaching any LLM.

What it does

Automatically detects and masks sensitive data in your prompts:

• 📧 Email addresses
• 📱 Phone numbers (India-friendly)
• 💳 Credit card numbers
• 🪪 Aadhaar numbers
• 📋 PAN cards
• 🌐 IP addresses
• 🛂 Passport numbers
• 🏦 Bank account numbers

How it works

Once installed, Claude Desktop (and Cursor/Windsurf) automatically has access to a scan_prompt tool. You can ask Claude to scan any prompt before sending it, or Claude will proactively suggest scanning when it detects potentially sensitive content.

Installation

Option 1 — Run directly with npx (no install needed)

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "ai-security-gateway": {
      "command": "npx",
      "args": ["-y", "ai-security-gateway-mcp"]
    }
  }
}

Option 2 — Install globally

npm install -g ai-security-gateway-mcp

Then add to claude_desktop_config.json:

{
  "mcpServers": {
    "ai-security-gateway": {
      "command": "ai-security-gateway-mcp"
    }
  }
}

Config file locations

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

Usage

After restarting Claude Desktop, try:

Scan this prompt for PII before I send it: [your text here]

Use REPLACE mode to anonymize: [your text here]

Is this safe to send to an LLM? [your text here]

Anonymization modes

Mode	Behaviour	Example
MASK	Partially hides values	j***@g***.com
REDACT	Removes values entirely	(empty)
REPLACE	Substitutes typed tokens	[EMAIL], [AADHAAR]

Works with

• Claude Desktop (macOS and Windows)
• Cursor
• Windsurf
• Any MCP-compatible client

Privacy

All detection runs locally on your machine. No data is sent to any server or cloud service.

Development

npm install
npm run build   # compile TypeScript → dist/
npm run dev     # run via tsx (no compile step)
npm start       # run compiled output

Related

• Web app (v1): https://github.com/dceptev-byte/ai_security_gateway