@wundervault/mcp-server

MCP server for Wundervault zero-knowledge secret management. Exposes vault secrets to AI agents via the Model Context Protocol — secrets are decrypted server-side and never returned to the agent in plaintext.

Install

npm install -g @wundervault/mcp-server

Quick Start

{
  "mcpServers": {
    "wundervault": {
      "command": "wundervault-mcp",
      "env": {
        "WUNDERVault_AGENT_VAULT_URL": "https://wundervault.com",
        "WUNDERVault_AGENT_VAULT_API_KEY": "wv_agent_<AGENT_ID>|<KEY_SUFFIX>",
        "WUNDERVault_AGENT_KEY": "<BASE64_ENCRYPTION_KEY>"
      }
    }
  }
}

Or using a credentials file:

wundervault-mcp --credentials ~/.wundervault/creds.json

Security Model

• Zero-knowledge: The encryption key lives only in the MCP server process. The Wundervault server never sees it.
• Burn-after-reading: Plaintext secrets are never returned to the calling agent. After decryption, the agent receives only "Secret retrieved and burned.".
• Exec scrubbing: If you use the exec parameter, stdout/stderr are scrubbed of the plaintext before being returned.
• Directive integrity: Server-side directive signatures (PBKDF2-HMAC-SHA256, 600k iterations) are verified before any secret is released.
• Timing-safe: HMAC comparison uses crypto.timingSafeEqual.

Tools

vault_entries_list

List all vault entries available to this agent. Returns entry IDs and secret names — no values.

Input: {}
Output: "Vault entries (N):\n  [entry_id]  secret_name  (tier: read)"

vault_entry_get

Retrieve and decrypt a vault secret. Optionally execute a command with it.

Input:
  entry_id: string          # from vault_entries_list
  purpose: string           # audit log reason
  exec?: string             # optional shell command

Output: "Secret retrieved and burned." (plaintext NEVER returned)

Secure exec pattern (sudo example):

sudo -S systemctl restart nginx <<< "$WUNDERVault_SECRET"

Do NOT use echo $WUNDERVault_SECRET | sudo -S — that exposes the secret in process logs.

vault_entry_forget

Discard a local reference. No-op on the server.

Input: { entry_id: string }
Output: "Reference [id] discarded from local context."

Credential Loading Priority

1. CLI flags (--api-key, --enc-key, --url)
2. Environment variables (WUNDERVault_AGENT_VAULT_API_KEY, WUNDERVault_AGENT_KEY, WUNDERVault_AGENT_VAULT_URL)
3. WUNDERVault_CREDENTIALS_FILE env var (explicit path)
4. ~/.wundervault/creds.json
5. ~/.config/wundervault/credentials (XDG)

Credentials file format

{
  "agent_vault_url": "https://wundervault.com",
  "agent_vault_api_key": "wv_agent_<ID>|<SUFFIX>",
  "agent_encryption_key": "<BASE64_URL_SAFE_32_BYTES>"
}

CLI Options

wundervault-mcp [options]

  --api-key <key>     Agent API key
  --enc-key <key>     Encryption key (base64 URL-safe)
  --url <url>         API base URL (default: https://wundervault.com)
  --credentials <f>   Path to credentials JSON file
  --help              Show help

Building from source

git clone https://github.com/wundervault/wundervault-mcp.git
cd wundervault-mcp
npm install
npm run build   # compiles TypeScript to dist/
npm test        # run the test suite

License

Licensed under the GNU Affero General Public License v3.0 or later (AGPL-3.0-or-later). See LICENSE.

Wundervault is open-core: this MCP server and the client are open source; the hosted service at wundervault.com is a commercial offering. For commercial or hosting inquiries, get in touch via wundervault.com/contact.