MCP LNC Server

Build and configure the MCP server that connects AI assistants to Lightning nodes via Lightning Node Connect (LNC). LNC uses encrypted WebSocket tunnels through a mailbox relay, so the agent never needs direct gRPC access, TLS certificates, or macaroons — just a 10-word pairing phrase from Lightning Terminal.

The MCP server is read-only by default — it exposes 18 tools for querying node state but cannot send payments or modify channels.

Quick Start

# 1. Build the MCP server binary
skills/lightning-mcp-server/scripts/install.sh

# 2. Configure environment (mailbox server, dev mode, etc.)
skills/lightning-mcp-server/scripts/configure.sh

# 3. Add to Claude Code as an MCP server
skills/lightning-mcp-server/scripts/setup-claude-config.sh

Then restart Claude Code. The lnc_connect tool will be available to connect to any lnd node using a pairing phrase.

How It Works

Claude Code  \x3C--stdio-->  lightning-mcp-server  \x3C--LNC WebSocket-->  Mailbox  \x3C-->  lnd

1. Claude Code launches lightning-mcp-server as a subprocess (stdio transport)
2. Agent calls lnc_connect with a pairing phrase and password
3. Server generates an ephemeral ECDSA keypair and opens an encrypted WebSocket tunnel through the mailbox relay
4. Once connected, the agent can call any of the 18 read-only tools
5. lnc_disconnect closes the tunnel

No keys, certs, or macaroons are stored on disk — the pairing phrase is the only credential, and it's handled in-memory only.

Installation

# Build from source (requires Go 1.24+)
skills/lightning-mcp-server/scripts/install.sh

# Verify
lightning-mcp-server -version

The install script builds from the lightning-mcp-server/ directory in this repo.

Configuration

# Generate .env with defaults
skills/lightning-mcp-server/scripts/configure.sh

# Production (mainnet via Lightning Terminal)
skills/lightning-mcp-server/scripts/configure.sh --production

# Development (local regtest)
skills/lightning-mcp-server/scripts/configure.sh --dev --mailbox aperture:11110

Configuration is stored in lightning-mcp-server/.env. Key settings:

Claude Code Integration

Option 1: claude mcp add (recommended)

Register the MCP server with a single command — no build step required:

# Zero-install via npx (downloads pre-built binary)
claude mcp add --transport stdio lnc -- npx -y @lightninglabs/lightning-mcp-server

# With environment variables for production
claude mcp add --transport stdio \
  --env LNC_MAILBOX_SERVER=mailbox.terminal.lightning.today:443 \
  lnc -- npx -y @lightninglabs/lightning-mcp-server

# For development/regtest
claude mcp add --transport stdio \
  --env LNC_MAILBOX_SERVER=localhost:11110 \
  --env LNC_DEV_MODE=true \
  --env LNC_INSECURE=true \
  lnc -- npx -y @lightninglabs/lightning-mcp-server

Scope options: --scope local (default, just you), --scope project (shared via .mcp.json), --scope user (all your projects).

Option 2: Setup script (from source)

# Add lightning-mcp-server to Claude Code's MCP config
skills/lightning-mcp-server/scripts/setup-claude-config.sh

# Project-level config (current project only)
skills/lightning-mcp-server/scripts/setup-claude-config.sh --scope project

# Global config (all projects)
skills/lightning-mcp-server/scripts/setup-claude-config.sh --scope global

This adds the server to Claude Code's .mcp.json (project) or ~/.claude.json (global) configuration. After restarting Claude Code, the LNC tools will be available.

Option 3: Manual configuration

Add to .mcp.json in your project root:

{
  "mcpServers": {
    "lnc": {
      "command": "npx",
      "args": ["-y", "@lightninglabs/lightning-mcp-server"],
      "env": {
        "LNC_MAILBOX_SERVER": "mailbox.terminal.lightning.today:443"
      }
    }
  }
}

Or with a locally built binary:

{
  "mcpServers": {
    "lnc": {
      "command": "lightning-mcp-server",
      "env": {
        "LNC_MAILBOX_SERVER": "mailbox.terminal.lightning.today:443"
      }
    }
  }
}

Or run via Docker:

{
  "mcpServers": {
    "lnc": {
      "command": "docker",
      "args": [
        "run", "--rm", "-i", "--network", "host",
        "--env", "LNC_MAILBOX_SERVER",
        "--env", "LNC_DEV_MODE",
        "--env", "LNC_INSECURE",
        "lightning-mcp-server"
      ]
    }
  }
}

Available Tools (18)

Connection

Node

Channels

Invoices

Payments

Peers & Network

On-Chain

Security Model

• No stored credentials: Pairing phrase is handled in-memory only. Ephemeral ECDSA keypairs are generated per session.
• Read-only: No payment, channel, or state-changing operations are exposed. The agent can observe but not modify.
• Encrypted tunnels: All traffic is encrypted end-to-end through the mailbox relay. The mailbox cannot read the traffic.
• No direct access: The agent machine never connects directly to the lnd node's gRPC port — all traffic goes through the mailbox.

Comparison with Direct gRPC Access

Prerequisites

• Go 1.24+ for building from source
• Lightning Terminal (litd) on the target node for generating pairing phrases
• Claude Code for MCP integration

Troubleshooting

"pairing phrase must be exactly 10 words"

The pairing phrase is generated by Lightning Terminal. It must be exactly 10 space-separated words.

"connection timeout"

Check that the mailbox server is reachable. For production, ensure mailbox.terminal.lightning.today:443 is not blocked by a firewall.

"TLS handshake failure"

If using a local regtest setup, enable dev mode and insecure mode:

skills/lightning-mcp-server/scripts/configure.sh --dev --insecure

Tools not appearing in Claude Code

Restart Claude Code after running setup-claude-config.sh. Check that lightning-mcp-server is on your $PATH:

which lightning-mcp-server