lightning-enable-mcp 1.3.0

MCP server for L402 Lightning payments - access paid APIs with AI agents

Lightning Enable MCP Server

An MCP (Model Context Protocol) server that enables AI agents to access L402-protected APIs with automatic Lightning Network payments.

Overview

Lightning Enable MCP provides tools for AI agents (like Claude) to:

• Access paid APIs - Automatically handle L402 payment challenges
• Manage Lightning payments - Pay invoices via Nostr Wallet Connect (NWC)
• Control spending - Set per-request and session budgets
• Track payments - View payment history and wallet balance

Installation

Using pip

pip install lightning-enable-mcp

Using uvx (recommended for Claude Desktop)

No installation needed - uvx handles it automatically.

Configuration

Environment Variables

Variable	Required	Default	Description
NWC_CONNECTION_STRING	Yes*	-	Nostr Wallet Connect URI
OPENNODE_API_KEY	Yes*	-	OpenNode API key (alternative to NWC)
OPENNODE_ENVIRONMENT	No	production	"production" or "dev" for testnet
L402_MAX_SATS_PER_REQUEST	No	1000	Maximum sats per single request
L402_MAX_SATS_PER_SESSION	No	10000	Maximum sats for entire session

*Either NWC_CONNECTION_STRING or OPENNODE_API_KEY is required. NWC takes precedence if both are set.

Wallet Options

Option 1: OpenNode (Recommended for Testing)

Use your OpenNode account to pay invoices. Great for testing since you likely already have an OpenNode account if you're using Lightning Enable.

1. Get your API key from https://app.opennode.com (or https://app.dev.opennode.com for testnet)
2. Ensure the API key has withdrawal permissions
3. Fund your OpenNode account

export OPENNODE_API_KEY="your-api-key"
export OPENNODE_ENVIRONMENT="dev"  # Use testnet for testing

Option 2: Nostr Wallet Connect (NWC)

NWC allows this server to pay invoices using your Lightning wallet. You can get a connection string from:

1. Alby - https://getalby.com (Browser extension or Alby Hub)
2. Mutiny Wallet - https://mutinywallet.com
3. Coinos - https://coinos.io
4. Any NWC-compatible wallet

The connection string looks like:

nostr+walletconnect://pubkey?relay=wss://relay.example.com&secret=hexsecret

Claude Desktop Configuration

Add to your Claude Desktop config (claude_desktop_config.json):

Using OpenNode:

{
  "mcpServers": {
    "lightning-enable": {
      "command": "uvx",
      "args": ["lightning-enable-mcp"],
      "env": {
        "OPENNODE_API_KEY": "your-opennode-api-key",
        "OPENNODE_ENVIRONMENT": "dev"
      }
    }
  }
}

Using NWC:

{
  "mcpServers": {
    "lightning-enable": {
      "command": "uvx",
      "args": ["lightning-enable-mcp"],
      "env": {
        "NWC_CONNECTION_STRING": "nostr+walletconnect://your-pubkey?relay=wss://relay.getalby.com/v1&secret=your-secret"
      }
    }
  }
}

Or if installed via pip, replace "command": "uvx", "args": ["lightning-enable-mcp"] with just "command": "lightning-enable-mcp".

Available Tools

access_l402_resource

Fetch a URL with automatic L402 payment handling.

Parameters:

Name	Type	Required	Default	Description
url	string	Yes	-	The URL to fetch
method	string	No	GET	HTTP method (GET, POST, PUT, DELETE)
headers	object	No	{}	Additional request headers
body	string	No	-	Request body for POST/PUT
max_sats	integer	No	1000	Maximum sats to pay for this request

Example:

Use access_l402_resource to fetch https://api.example.com/premium-data

Returns: Response body text or error message

pay_l402_challenge

Manually pay an L402 invoice and get the authorization token.

Parameters:

Name	Type	Required	Default	Description
invoice	string	Yes	-	BOLT11 invoice string
macaroon	string	Yes	-	Base64-encoded macaroon from L402 challenge
max_sats	integer	No	1000	Maximum sats allowed for this payment

Returns: L402 token in format macaroon:preimage for use in Authorization header

check_wallet_balance

Check the connected wallet balance via NWC.

Parameters: None

Returns: Current balance in satoshis

get_payment_history

List recent L402 payments made during this session.

Parameters:

Name	Type	Required	Default	Description
limit	integer	No	10	Maximum number of payments to return
since	string	No	-	ISO timestamp to filter payments from

Returns: List of payments with url, amount, timestamp, and status

configure_budget

Set spending limits for the session.

Parameters:

Name	Type	Required	Default	Description
per_request	integer	No	1000	Maximum sats per individual request
per_session	integer	No	10000	Maximum total sats for the session

Returns: Confirmation of new limits

pay_invoice

Pay a Lightning invoice directly and get the preimage as proof of payment. Use this to pay any BOLT11 Lightning invoice without L402 protocol overhead.

Parameters:

Name	Type	Required	Default	Description
invoice	string	Yes	-	BOLT11 Lightning invoice string to pay
max_sats	integer	No	1000	Maximum sats allowed to pay

Example:

Use pay_invoice to pay lnbc100n1pj9npjpp5... with max_sats 500

Returns: JSON with payment result including:

• success: boolean - Whether payment succeeded
• preimage: string - Payment preimage (proof of payment)
• message: string - Status message
• invoice.paid: string - Truncated invoice that was paid

How L402 Works

L402 (formerly LSAT) is a protocol for API monetization using Lightning Network:

1. Client requests a resource
2. Server returns 402 Payment Required with a WWW-Authenticate header containing:
   • A macaroon (authorization token)
   • A BOLT11 Lightning invoice
3. Client pays the invoice, receiving a preimage
4. Client retries the request with Authorization: L402 <macaroon>:<preimage>
5. Server validates and returns the resource

This MCP server handles steps 2-5 automatically when you use access_l402_resource.

Security Considerations

• Budget Limits: Always set appropriate spending limits for your use case
• NWC Secret: Keep your NWC connection string secure - it allows payments from your wallet
• Session Isolation: Each server instance maintains its own budget and payment history
• Invoice Verification: The server verifies invoice amounts before paying

Development

Setup

git clone https://github.com/refinedelement/lightning-enable-mcp
cd lightning-enable-mcp
pip install -e ".[dev]"

Running Tests

pytest

Type Checking

mypy src/lightning_enable_mcp

Linting

ruff check src/
ruff format src/

Architecture

lightning_enable_mcp/
├── server.py          # Main MCP server and tool registration
├── l402_client.py     # L402 protocol implementation
├── nwc_wallet.py      # Nostr Wallet Connect client
├── budget.py          # Spending limit management
└── tools/
    ├── access_resource.py   # access_l402_resource tool
    ├── pay_challenge.py     # pay_l402_challenge tool
    ├── wallet.py            # check_wallet_balance tool
    └── budget.py            # configure_budget, get_payment_history tools

License

MIT License - see LICENSE for details.

Support

• Issues: https://github.com/refinedelement/lightning-enable-mcp/issues
• Documentation: https://lightningenable.com/docs
• Discord: https://discord.gg/lightningenable

Related Projects

• Lightning Enable - Bitcoin Lightning payment API middleware
• MCP Specification - Model Context Protocol
• NIP-47 - Nostr Wallet Connect