PhantomAuth

MCP server that fills web forms with secrets from SecureVault — AI agents never see raw credentials.

How it works

PhantomAuth sits between your AI agent and Microsoft's Playwright MCP:

AI Agent → PhantomAuth MCP → Playwright MCP → Browser
               ↕
          SecureVault (OS Keychain)

1. Agent calls secure_fill("Microsoft Email", "#email-input")
2. PhantomAuth resolves "Microsoft Email" from SecureVault's OS keychain
3. The raw value is forwarded directly to Playwright MCP's browser_fill_form
4. Agent only sees "✅ Filled — value hidden from agent"

The agent never sees the actual password, token, or credential.

Prerequisites

• SecureVault installed with secrets in the OS keychain
• Playwright MCP running in HTTP mode:

  npx @playwright/mcp@latest --port 8931 --shared-browser-context
  

Setup

Add to your MCP client configuration (e.g. VS Code mcp.json):

{
  "mcpServers": {
    "phantomauth": {
      "command": "node",
      "args": ["C:/src/PhantomAuth/index.js"],
      "env": {
        "PLAYWRIGHT_MCP_URL": "http://localhost:8931/mcp"
      }
    }
  }
}

Tools

secure_fill

Fill a form field with a secret. Uses Playwright's fill (sets value directly).

secure_fill(secretTitle: "My Password", selector: "#password")

secure_type

Type a secret into a field keystroke-by-keystroke. Use for React-controlled inputs.

secure_type(secretTitle: "TOTP Code", selector: "#otp-input", pressEnterAfter: true)

secure_authenticate

Multi-step login flow using a SecureVault profile.

secure_authenticate(
  profileName: "Microsoft",
  steps: [
    { selector: "#email", envVar: "EMAIL", action: "fill" },
    { selector: "#password", envVar: "PASSWORD", action: "fill", pressEnterAfter: true, waitMs: 2000 }
  ]
)

list_vault_secrets

List available secret names (values are never exposed).

list_vault_profiles

List profiles and their env var → secret mappings.

Configuration

Environment Variable	Default	Description
PLAYWRIGHT_MCP_URL	http://localhost:8931/mcp	URL of the Playwright MCP HTTP endpoint

License

MIT

AI Agent Skills

PhantomAuth includes instruction files that teach AI agents how to use the tools:

File	Agent	Description
.github/copilot-instructions.md	GitHub Copilot	Custom instructions loaded automatically by Copilot
.claude/skills/phantomauth.md	Claude Code	Skill file discovered by Claude Code
SKILL.md	Universal	Cross-agent skill file (agentskills.io format)

Using with agentskills CLI

npx agentskills export --target copilot
npx agentskills export --target claude