Step 1: Install the MCP proxy

npm install -g tyga-mcp-proxy

Then add it to your MCP configuration. For Claude Code, edit ~/.claude/mcp.json:

{
  "mcpServers": {
    "my-server": {
      "command": "tyga-mcp-proxy",
      "args": ["--api-key", "a2a_YOUR_KEY", "--", "node", "my-server.js"]
    }
  }
}

The -- separates proxy args from your MCP server command. Everything after -- is the server that gets wrapped.

Step 2: How it works

The proxy spawns your MCP server as a subprocess and pipes stdio through the safety shield:

// What happens under the hood:
// 1. MCP client sends tools/call { "name": "shell", "arguments": { "command": "rm -rf /" } }
// 2. tyga-mcp-proxy intercepts the JSON-RPC message
// 3. Extracts the command, runs Gate 1 (regex denylist, <5ms)
// 4. If --api-key set: also runs Gate 2 (LLM judge via /v1/evaluate)
// 5. If allowed → forward to your MCP server
// 6. If blocked → return error to client, command never runs

Local mode (no API key)

Gate 1 only. Zero latency, zero cost. No network calls.

tyga-mcp-proxy -- node my-server.js

Cloud mode (with API key)

Gate 1 + Gate 2 + OCSF audit trail.

tyga-mcp-proxy --api-key a2a_YOUR_KEY -- node my-server.js

Step 3: Verify

Test the proxy directly from the command line:

# Check the proxy starts and shows help:
npx tyga-mcp-proxy --help
# Usage: tyga-mcp-proxy [options] -- <mcp-server-command> [args...]

# Test Gate 1 locally (Node.js):
node -e "
  const { SafetyShield } = require('tyga-mcp-proxy');
  const fw = new SafetyShield();
  console.log(fw.evaluate('rm -rf /'));
  // { allowed: false, reason: 'Safety Gate 1: matched [rm\\s+-rf\\s+\\/]' }
  console.log(fw.evaluate('ls -la'));
  // { allowed: true }
"

For Cursor or Windsurf, add the same server block to their respective MCP config files.