@voltanotes/mcp

MCP server for Volta Notes — create and read burn-after-read encrypted notes from any AI agent.

Notes are end-to-end encrypted using AES-256-GCM. The decryption key lives only in the URL fragment — it is never sent to any server. Notes are stored on the Internet Computer and permanently destroyed after a single read.

Why

AI agents regularly need sensitive information at runtime — API keys, passwords, credentials. Today, users paste these into chat where they're stored permanently in conversation history.

With this MCP server, the pattern becomes:

1. User creates a note at voltanotes.com and sends the one-time URL
2. Agent calls read_volta_note — secret returned, note permanently destroyed
3. Nothing sensitive ever appears in chat history

Or in reverse — an agent can use create_volta_note to send credentials to a user via a self-destructing link.

Quick Start

Claude Code (CLI & Desktop App)

Step 1 — Install globally:

npm install -g @voltanotes/mcp

Step 2 — Register the server:

claude mcp add -s user volta -- node $(npm root -g)/@voltanotes/mcp/dist/index.js

That's it. Restart Claude Code and the create_volta_note and read_volta_note tools will be available.

Why claude mcp add instead of editing config files? Claude Code reads MCP servers from its own registry, not from ~/.claude/mcp.json. Using the CLI ensures the server is registered correctly. The -s user flag makes it available across all projects.

node not found? Use the full path: replace node with the output of which node (e.g. /usr/local/bin/node).

Claude Desktop (Standalone)

Add to your claude_desktop_config.json:

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

Other MCP-compatible clients

The npx config above works with any client that supports the standard command/args MCP format — including Cursor, Windsurf, Cline, Continue.dev, and others. Check your client's MCP documentation for where to add server config.

Windows (Claude Code CLI)

The $(npm root -g) syntax doesn't work in PowerShell or CMD. Use this instead:

claude mcp add -s user volta -- node "%APPDATA%\npm\node_modules\@voltanotes\mcp\dist\index.js"

Or use the Claude Desktop / npx method above, which works cross-platform.

Tools

create_volta_note

Creates an encrypted note and returns a one-time URL.

| Parameter | Type | Description | |-----------|--------|--------------------------------------| | content | string | Secret content to encrypt (max 2 KB) |

Returns: A voltanotes.com URL. The recipient opens it once, reads the content, and it's gone forever.

read_volta_note

Reads and permanently destroys a Volta note.

| Parameter | Type | Description | |-----------|--------|----------------------------------------| | url | string | Full Volta URL including # fragment |

Returns: The decrypted note content. The note is permanently deleted from the canister — a second read will fail.

Agent Prompt Snippet

Add this to any agent's system prompt to enable secure credential handoff:

When you need a secret from the user (API key, password, credentials):
1. Ask them to go to voltanotes.com and paste the secret into the note field
2. They'll get a one-time URL — ask them to send it to you
3. Use the read_volta_note tool with that URL to retrieve the secret
The secret is permanently destroyed after you read it — it never appears in chat history.

Security Model

• AES-256-GCM encryption happens locally before anything is sent to the canister
• The encryption key exists only in the URL fragment (#...) — browsers and servers never transmit fragments
• The ICP canister stores only ciphertext — even if compromised, all data is unreadable
• Notes are destroyed on first read. Unread notes expire after 7 days.
• No accounts, no login, no tracking

How It Works

Agent calls create_volta_note("secret-api-key-123")
  → Local: generate AES-256 key + encrypt
  → ICP canister: store ciphertext → returns noteId
  → Return URL: voltanotes.com/r/{noteId}#{key}

User opens URL → read gate → clicks "Read note"
  → Browser: fetch ciphertext from canister (canister deletes it)
  → Browser: decrypt using key from # fragment
  → Display plaintext — note is gone forever

Troubleshooting

Check if the server is connected

claude mcp list

You should see volta: ... ✓ Connected. If not, see below.

Server not showing up

1. Did you use claude mcp add? Editing ~/.claude/mcp.json manually won't work — Claude Code reads servers from its own registry. Always use claude mcp add to register servers.

2. Is node on your PATH? Claude Code's shell has a minimal PATH. If node isn't found, use the full path:

   claude mcp add -s user volta -- $(which node) $(npm root -g)/@voltanotes/mcp/dist/index.js

3. Restart required. After adding or changing an MCP server, fully restart Claude Code (quit and reopen).

How do I know if the server started?

The server logs Volta MCP server started to stderr on successful startup. Run claude mcp list to check connection status.

Requirements

• Node.js 18+ (uses built-in Web Crypto API)

License

MIT — Unprompted Labs