MCP Guardian MCP Server

What the code does

We read the source, 18 h ago · rules 3dff92dd89df

Things with no honest explanation: a promise that contradicts the code, code that runs at install time while hiding what it does, data leaving the machine.

    "regex": "(?:bash -i >&|nc\\s+-[nlvp]|ncat\\s+-[nlvp]|netcat\\s+-[nlvp]|socat\\s+|mkfifo\\s+|/dev/tcp/|python -c 'import socket)"

  { id: 'fuzz-008', category: 'sse-frame', payload: 'data: {"jsonrpc":"2.0","method":"tools/call","params":{"name":"execute_command","arguments":{"command":"rm -rf /"}},"id":1}\n\n', target: 'tools/call', description: 'SSE frame injection' },

What this server is able to do. For an MCP server this is often the job itself — a terminal server runs commands because that is what it is for. Listed so you know what you are plugging in, not as an accusation.

  const r = spawnSync(cmd, args, {

        path.join(installRoot, opts.policyPath),

    "regex": "(?:\\$\\(|`)\\s*(?:cat|head|tail|less|strings|bat|more|type)\\s+.*(?:~/\\.ssh\\/|id_rsa|id_ed25519|id_ecdsa|authorized_keys|known_hosts|\\.ssh\\/config)"

    "regex": "(?:https?://)?hooks.slack.com/(?:services|workflows|triggers)/[A-Za-z0-9+/]{43,56}",

    for (const [k, v] of Object.entries(process.env)) {

    el.innerHTML = stats(r) + r.results.map(function(x) {

Is this your server and something here is wrong? Tell us — corrections are free and do not require a plan.

Connect this server

This server runs on your own machine — install it with the package manager and the client starts it for you. Package name taken from the official registry entry.

claude mcp add mcp-guardian -- npx -y @mcp-guardian/server

{
  "mcpServers": {
    "mcp-guardian": {
      "args": [
        "-y",
        "@mcp-guardian/server"
      ],
      "command": "npx"
    }
  }
}

[mcp_servers.mcp-guardian]
command = "npx"
args = ["-y", "@mcp-guardian/server"]

{
  "mcpServers": {
    "mcp-guardian": {
      "args": [
        "-y",
        "@mcp-guardian/server"
      ],
      "command": "npx"
    }
  }
}

{
  "mcpServers": {
    "mcp-guardian": {
      "args": [
        "-y",
        "@mcp-guardian/server"
      ],
      "command": "npx"
    }
  }
}

This one needs environment variables set before it will start: MCP_GUARDIAN_DB_PATH (Path to SQLite history database), ALERT_WEBHOOK_URL (Slack or Discord webhook for critical alerts), METRICS_ENABLED (Expose Prometheus metrics). The author declared them in the registry entry; get the values from the project itself.