vault-mcp

MCP server that exposes secrets from your OS keychain (or an AES-256-GCM encrypted file) as MCP tools. Secrets are returned directly in tool results and never appear in conversation messages.

Tools

Tool	Description
get_secret(key)	Read a secret value from the vault
set_secret(key, value)	Store a secret in the vault
list_secrets()	List stored key names — values are never returned

Quick start

# Install deps
cd vault-mcp && npm install

# Walk through adding a first secret and get your config block
npx vault-mcp init
# (on Linux without libsecret, set passphrase first)
# export VAULT_MCP_PASSPHRASE="my-strong-passphrase"
# npx vault-mcp init

The init command prints a JSON block to paste into claude_desktop_config.json (Claude Desktop) or .claude/settings.json (Claude Code).

Backends

OS Keychain (keytar) — recommended on macOS / Windows

When keytar installs successfully and libsecret is available, secrets are stored in the OS keychain (Keychain Access on macOS, Credential Manager on Windows, Secret Service on Linux).

No environment variable needed.

AES-256-GCM file vault — Linux CI / containers

If keytar is unavailable, vault-mcp falls back to ~/.vault-mcp/vault.json. Each value is encrypted with AES-256-GCM using a key derived via scrypt from your passphrase.

export VAULT_MCP_PASSPHRASE="my-strong-passphrase"

Add this env var to your MCP server config (see init output).

Other CLI commands

vault-mcp set MY_SECRET "value"   # store without interactive prompt
vault-mcp list                     # print stored key names
vault-mcp server                   # start MCP server (used by config block)

MCP config example (file vault)

{
  "mcpServers": {
    "vault-mcp": {
      "command": "node",
      "args": ["/path/to/vault-mcp/src/server.js"],
      "env": {
        "VAULT_MCP_PASSPHRASE": "my-strong-passphrase"
      }
    }
  }
}