mcp-server-vault

@aiwerk/mcp-server-vault

Bitwarden / Vaultwarden MCP server — BYOK vault access for AI agents.

Exposes 6 tools over stdio. Secret values are never sent in plaintext through list_vault_items or get_vault_metadata — secrets are delivered only through Bitwarden Sends (E2E-encrypted one-time URLs).

Install

npx -y @aiwerk/mcp-server-vault

Configure

| Variable | Required | Default | Description | |---|---|---|---| | VAULT_API_BASE | ✅ | — | Base URL of your Bitwarden/Vaultwarden instance (no trailing slash), e.g. https://pass.aiwerk.ch | | VAULT_CLIENT_ID | ✅ | — | Personal API key client_id (e.g. user.abc-def-1234) | | VAULT_CLIENT_SECRET | ✅ | — | Personal API key client_secret | | VAULT_MASTER_PASSWORD | ✅ | — | Vault master password (used for E2E decryption key derivation) | | VAULT_EXPOSED_COLLECTION | — | mcp-exposed | Name of the collection visible to agents | | VAULT_AGENT_CREATED_COLLECTION | — | mcp-agent-created | Name of the collection for agent-created secrets | | VAULT_API_TIMEOUT_MS | — | 15000 | HTTP timeout in milliseconds | | DRY_RUN | — | 0 | Set 1 to log write operations without executing them | | READ_ONLY | — | 0 | Set 1 to block all write operations (Send creation and save) |

Auth — Personal API Key

1. Log in to your Bitwarden/Vaultwarden instance
2. Go to Account Settings → Security → Keys → API Key
3. Note the client_id and client_secret
4. Reference: https://bitwarden.com/help/personal-api-key/

Vault Setup

Before using this server, create two collections in your Vaultwarden organization:

• mcp-exposed — items you want to expose to agents (your existing secrets: API keys, passwords, etc.)
• mcp-agent-created — items written by agents via save_generated_secret

Add items to mcp-exposed via the Vaultwarden web UI.

Custom fields

Optionally add these custom fields to items in mcp-exposed for fine-grained control:

| Field | Type | Purpose | |---|---|---| | mcp-scope | text | Comma-separated glob list of tool/server names allowed to use this item (e.g. stripe.*,openai) | | mcp-chat-reveal-allowed | text | "true" to allow chat delivery of the Send URL | | mcp-delivery-channel | text | "chat" (default), "telegram", or "email" |

Tools

| Tool | Description | |---|---| | list_vault_items | List items from mcp-exposed and mcp-agent-created. Returns metadata only — no secret values. | | get_vault_metadata | Get full metadata for a named item (name, type, username, URIs, custom fields, expiry). No password/secret. | | reveal_secret_via_send | Reveal a secret via a Bitwarden Send (E2E-encrypted one-time URL with configurable TTL and max-views). | | get_totp_code | Get the current TOTP code for a login item, including remaining seconds in the period. | | save_generated_secret | Save an agent-generated secret (password / api-key) into mcp-agent-created as a secure note. CREATE-only — no overwrite. | | save_login_item | Save sign-in credentials (username + password + optional URL + TOTP seed) into mcp-agent-created as a real login item. CREATE-only — no overwrite. | | health_check | Check connectivity: auth status, API version, collection visibility, item counts, latency. |

Security model

• Opt-in exposure: only items in mcp-exposed or mcp-agent-created are accessible; all other items return item_not_visible
• Read-only existing items: no update_, delete_, or change_* tools exist
• Secret value delivery via Send only: list_vault_items and get_vault_metadata never return passwords, TOTP seeds, or api-key values
• E2E encryption preserved: the server decrypts vault data locally (master password stays in env vars, never sent over the wire)
• Constrained agent writes: save_generated_secret and save_login_item are CREATE-only into the dedicated mcp-agent-created collection

Note: Actual {{vault:NAME}} placeholder resolution in tool call arguments happens in the AIWerk hosted bridge, not in this server. The bridge's resolution uses the same BYOC credentials. See the bridge-patch companion document for details.

License

MIT — AIWerk <kontakt@aiwerk.ch>

Homepage: https://aiwerkmcp.com