@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.

Hermes Agent (Nous Research)

Volta MCP works with Hermes Agent via its MCP integration. Add the server to your Hermes config (~/.hermes/config.yaml):

mcp:
  servers:
    - name: volta
      command: npx
      args:
        - "-y"
        - "@voltanotes/mcp"

Restart Hermes and the create_volta_note and read_volta_note tools will be available to your agent.

Agent-to-agent use case: Hermes agents running autonomously often need to pass credentials between workflows without exposing them in logs or memory. Volta Notes is purpose-built for this — one agent creates a note, passes the one-time URL to the next, and the secret is destroyed on read. Nothing persists in conversation history or tool output logs.

See Hermes MCP documentation for full configuration options.

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