LiveAuth MCP Server

Authentication, pay-per-call metering, and signed receipts for AI agents and MCP tools: Bitcoin-native, Lightning-backed, and L402 compatible.

This MCP server lets any AI agent authenticate against your API using proof-of-work (free, no account) or Lightning Network micropayments (sats), then meter and monetize subsequent tool calls with per-call pricing, idempotent revenue events, and HMAC-signed receipts that auditors can verify offline.

Use it when you want to:

• Gate an API or MCP tool behind real cost-of-compute or real sats (anti-spam by design, not by CAPTCHA).

• Charge AI agents per call without signing them up for an account.

• Issue a tamper-evident audit trail (signed mcp-call-receipt-v1) for every paid tool invocation.

• Offer Lightning-backed L402 bundle access for prepaid MCP sessions.

Try it in 5 seconds — no account, no API key:

npx @liveauth-labs/mcp-server

Runs in demo mode (real Lightning invoice, simulated confirmation). Drop in your LIVEAUTH_API_KEY to go live.

Available Tools (Glama / MCP auto-discovered)

Full parameter and response schemas are in the Tool Reference below.

Related MCP server: Agent Receipts

5-Minute Quick Start

Option 1 — Demo Mode (no account, no key)

npx @liveauth-labs/mcp-server

Returns a real Lightning invoice (so you can see the payment flow) but confirmation is simulated. Free, no signup.

Option 2 — Production Mode

1. Grab an API key at liveauth.app.

2. Add to Claude Desktop's claude_desktop_config.json:

{
  "mcpServers": {
    "liveauth": {
      "command": "npx",
      "args": ["-y", "@liveauth-labs/mcp-server"],
      "env": {
        "LIVEAUTH_API_BASE": "https://api.liveauth.app",
        "LIVEAUTH_API_KEY": "la_pk_your_public_key"
      }
    }
  }
}

3. Restart Claude. Done.

Option 3 — Programmatic (CLI / SDK)

export LIVEAUTH_API_KEY=la_pk_xxx
npx @liveauth-labs/mcp-server

The package is also a TypeScript SDK — see SDK Usage below. The CLI bin is liveauth-mcp.

Why LiveAuth?

For API providers / tool developers:

• Stop bots at the protocol layer. PoW and Lightning sats are non-replayable, non-phishable, and don't require user accounts.

• Charge per call in sats. We sign a receipt you can show auditors, your customers, or your accountant.

• Wrap any MCP tool with one line (createMcpGate) and you get per-tool revenue, per-tool min/max pricing, and idempotent retries.

For AI agents / agent builders:

• Permissionless access to paid APIs — solve a PoW or pay sats, get a JWT. No signup, no email, no OAuth dance.

• Use PoW, Lightning invoices, or L402 bundle macaroons for agent access.

• Projects can settle through a custom Lightning node when configured; otherwise payments use the LiveAuthCore-configured node.

The math that matters: if your tool is being scraped by a bot, charging 1 sat per call is enough to make the scraper unprofitable. We call this cost-of-attack economics, and it's the whole reason we exist.

Installation

npm install -g @liveauth-labs/mcp-server

Or use directly with npx:

npx @liveauth-labs/mcp-server

SDK Usage

The package can also be imported as a TypeScript/JavaScript SDK. Importing the package does not start the stdio MCP server; the CLI lives at the liveauth-mcp bin.

Client Auth Helper

import { createMcpClient } from '@liveauth-labs/mcp-server';

const liveauth = createMcpClient({
  publicKey: 'la_pk_xxx',
  baseUrl: 'https://api.liveauth.app',
  onInvoice(invoice) {
    // Render invoice.bolt11 as a QR code for a paid Lightning test.
    console.log(invoice.bolt11);
  },
});

const session = await liveauth.start();
const token = await liveauth.confirm(session);

console.log(token.jwt);

The client stores confirmed JWTs, refreshes them before expiry when a refresh token is returned, and exposes the current token through liveauth.token. Call liveauth.destroy() when your app is shutting down to clear token state and refresh timers.

To require a real paid invoice:

const session = await liveauth.start({ forceLightning: true });
console.log(session.invoice?.bolt11);

// Poll this after the invoice is paid.
const token = await liveauth.confirmLightning(session);

Server Gate Helper

import { createMcpGate } from '@liveauth-labs/mcp-server';

const gate = createMcpGate({
  publicKey: 'la_pk_xxx',
  baseUrl: 'https://api.liveauth.app',
});

const result = await gate.invoke(
  jwtFromYourTransport,
  { message: 'hello' },
  async (input, context) => ({
    content: [{ type: 'text', text: input.message }],
    charge: context.liveAuth.charge,
  }),
  {}
);

gate.invoke(...) validates the JWT, charges the configured sats cost or the backend project default, and passes context.liveAuth into your handler. The older gate.gateTool(...) name is still supported.

Paid Tool Attribution

If your MCP server has a registered LiveAuth tool ID, pass toolId when creating the gate. Charges then go to:

POST /api/mcp/tools/{toolId}/charge

instead of the legacy generic endpoint:

POST /api/mcp/charge

You can also pass a registered tool slug/name as toolName. In that mode charges go to the generic endpoint with tool identity in the body:

POST /api/mcp/charge

Tool charges preserve the same session budget checks, but also record an immutable revenue event with gross sats, LiveAuth platform fee, developer net sats, tool method name, paying project/session/token, metadata, and idempotency key. When costSats is omitted, LiveAuthCore uses the registered tool's default price; without toolId or toolName, it falls back to the project's global MCP price.

import { createMcpGate } from '@liveauth-labs/mcp-server';

const gate = createMcpGate({
  publicKey: process.env.LIVEAUTH_PUBLIC_KEY!,
  baseUrl: process.env.LIVEAUTH_API_URL ?? 'https://api.liveauth.app',
  toolName: 'paid-research-tool',
});

const result = await gate.invoke(
  jwtFromYourTransport,
  { url: 'https://example.com' },
  async (input, context) => {
    const page = await fetch(input.url).then(r => r.text());

    return {
      text: page,
      revenueEventId: context.liveAuth.charge.revenueEventId,
      receipt: context.liveAuth.charge.receipt,
      netSats: context.liveAuth.charge.netSats,
    };
  },
  { requestId: 'req_123' },
  {
    toolMethodName: 'web_fetch',
    idempotencyKey: 'req_123',
    agentId: 'agent_abc',
    metadata: {
      urlHost: new URL('https://example.com').hostname,
    },
  }
);

When toolId or toolName is set, GateToolOptions supports:

Tool charge responses include the normal budget counters plus revenue accounting:

{
  "status": "ok",
  "callsUsed": 3,
  "satsUsed": 15,
  "grossSats": 5,
  "platformFeeSats": 1,
  "netSats": 4,
  "feeBasisPoints": 500,
  "revenueEventId": "event-guid",
  "toolId": "tool-guid",
  "toolName": "Paid Research Tool",
  "toolSlug": "paid-research-tool",
  "receipt": {
    "version": "mcp-call-receipt-v1",
    "payload": "base64url-canonical-json",
    "signature": "base64url-hmac-sha256",
    "signatureAlgorithm": "HMAC-SHA256",
    "keyId": "liveauth-mcp-receipt-v1",
    "body": {
      "receiptId": "mcp_receipt_eventguid",
      "revenueEventId": "event-guid",
      "mcpToolId": "tool-guid",
      "toolName": "Paid Research Tool",
      "toolSlug": "paid-research-tool",
      "toolMethodName": "web_fetch",
      "grossSats": 5,
      "platformFeeSats": 1,
      "netSats": 4,
      "idempotencyKey": "req_123"
    }
  }
}

The receipt is a signed per-call audit artifact returned by LiveAuthCore for paid tool charges. Store it with your tool result when you need proof of charge or later reconciliation.

If no toolId or toolName is configured, the SDK keeps using /api/mcp/charge for backward-compatible usage metering.

Configuration

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "liveauth": {
      "command": "npx",
      "args": ["-y", "@liveauth-labs/mcp-server"],
      "env": {
        "LIVEAUTH_API_BASE": "https://api.liveauth.app",
        "LIVEAUTH_API_KEY": "la_pk_your_public_key"
      }
    }
  }
}

Demo Mode: If you omit LIVEAUTH_API_KEY or set LIVEAUTH_DEMO=true, the server uses the public demo auth endpoint and returns a 3-sat Lightning invoice preview. Confirmation is simulated by this MCP wrapper, so it is useful for testing without an account.

Other env vars:

Other MCP Clients

The server speaks stdio (JSON-RPC 2.0). Start it with:

liveauth-mcp

It also works with any MCP-compatible client: Cursor, VS Code, ChatGPT, Windsurf, Continue, Cline.

Tool Reference

Full schemas for each MCP tool. Each tool is JSON-RPC 2.0 compatible and tested under src/index.test.ts and src/cli.test.ts.

liveauth_mcp_start

Start a new LiveAuth MCP session. Returns a PoW challenge by default, or a Lightning invoice if forceLightning=true.

Parameters:

• forceLightning (boolean, optional): If true, request Lightning invoice instead of PoW challenge

• forceL402 (boolean, optional): If true, start a session that should be confirmed with an L402 bundle macaroon

Returns (PoW):

{
  "quoteId": "uuid-of-session",
  "powChallenge": {
    "projectId": "guid",
    "projectPublicKey": "la_pk_...",
    "challengeHex": "a1b2c3...",
    "targetHex": "0000ffff...",
    "difficultyBits": 18,
    "expiresAtUnix": 1234567890,
    "signature": "sig..."
  },
  "invoice": null
}

Returns (Lightning):

{
  "quoteId": "uuid-of-session",
  "powChallenge": null,
  "invoice": {
    "bolt11": "lnbc...",
    "amountSats": 50,
    "expiresAtUnix": 1234567890,
    "paymentHash": "abc123..."
  }
}

Returns (L402 bundle):

{
  "quoteId": "uuid-of-session",
  "powChallenge": null,
  "invoice": null,
  "authHint": "l402_bundle"
}

liveauth_mcp_confirm

Submit the solved proof-of-work challenge, poll a Lightning payment, or present an L402 macaroon to receive a JWT authentication token.

Parameters:

• quoteId (string): The quoteId from the start response

• challengeHex (string, PoW only): The challenge hex from the start response

• nonce (number, PoW only): The nonce that solves the PoW challenge

• hashHex (string, PoW only): The resulting hash (sha256 of projectPublicKey:challengeHex:nonce)

• expiresAtUnix (number, PoW only): Expiration timestamp from the challenge

• difficultyBits (number, PoW only): Difficulty bits from the challenge

• signature (string, PoW only): Signature from the challenge

• macaroon (string, L402 only): Bundle macaroon returned from the L402 bundle claim flow

Returns:

{
  "jwt": "eyJhbGc...",
  "expiresIn": 600,
  "remainingBudgetSats": 10000,
  "refreshToken": "abc123def456..."
}

Note: Save the refreshToken! Use liveauth_mcp_refresh to get a new JWT without re-authenticating.

liveauth_mcp_charge

Meter API usage after making an authenticated call. The bundled MCP server calls the generic /api/mcp/charge endpoint. Supplying toolName lets LiveAuth resolve a registered tool, apply its configured price, and create a paid-tool revenue event; omitting toolName keeps backward-compatible generic metering.

Parameters:

• callCostSats (number, optional): Cost of the API call in sats. Omit to use backend pricing.

• toolName (string, optional): Registered MCP tool slug/name for per-tool pricing and attribution.

Returns:

{
  "status": "ok",
  "callsUsed": 5,
  "satsUsed": 15
}

If budget is exceeded:

{
  "status": "deny",
  "callsUsed": 100,
  "satsUsed": 1000,
  "reason": "budget_exceeded"
}

liveauth_mcp_status

Check the status of an MCP session. Use to poll for Lightning payment confirmation.

Parameters:

• quoteId (string): The quoteId from the start response

Returns:

{
  "quoteId": "uuid-of-session",
  "status": "pending",
  "paymentStatus": "pending",
  "expiresAt": "2026-02-17T12:00:00Z"
}

When paymentStatus is "paid", the session is confirmed. Call liveauth_mcp_confirm again to get the JWT.

liveauth_mcp_lnurl

Get the Lightning invoice for a session (lnget-compatible). Use this to retrieve the BOLT11 invoice for payment with any Lightning wallet.

Parameters:

• quoteId (string): The quoteId from the start response

Returns:

{
  "pr": "lnbc2100n1...",
  "routes": []
}

Note: This is compatible with lnget and other Lightning payment tools. Use this to poll for the invoice when liveauth_mcp_confirm returns "payment pending".

liveauth_mcp_usage

Query current usage and remaining budget without making a charge. Use this to check status before making API calls.

Parameters: (none required)

Returns:

{
  "status": "active",
  "callsUsed": 5,
  "satsUsed": 15,
  "maxSatsPerDay": 10000,
  "remainingBudgetSats": 9985,
  "maxCallsPerMinute": 60,
  "expiresAt": "2026-02-17T12:00:00Z",
  "dayWindowStart": "2026-02-17T00:00:00Z"
}

liveauth_mcp_refresh

Refresh the JWT token without re-authenticating. Use the refreshToken returned from confirm to get a new JWT when the current one expires.

Parameters:

• refreshToken (string): The refreshToken from the confirm response

Returns:

{
  "jwt": "eyJhbGc...",
  "expiresIn": 600,
  "remainingBudgetSats": 9985
}

Note: Save the refreshToken securely. You'll need it to extend the session without solving a new PoW or making another Lightning payment.

Usage Example

PoW Authentication

1. Call liveauth_mcp_start to get a PoW challenge and quoteId

2. Solve the PoW challenge:

   • Compute hash = sha256(projectPublicKey:challengeHex:nonce)

   • Find a nonce where hash < targetHex

3. Call liveauth_mcp_confirm with the solution to receive a JWT

4. Use the JWT in Authorization: Bearer <token> header for API requests

5. After each generic API call, call liveauth_mcp_charge with a call cost, or omit it to use the project global MCP price

6. For monetized MCP tools, wrap handlers with createMcpGate({ toolId }) or createMcpGate({ toolName }) so each call creates a revenue event and signed receipt

Lightning Authentication

1. Call liveauth_mcp_start with forceLightning: true to get a Lightning invoice

2. Use liveauth_mcp_lnurl (or poll liveauth_mcp_status) to get the BOLT11 invoice

3. Pay the invoice using your Lightning node/wallet

4. Poll liveauth_mcp_status with the quoteId until paymentStatus is "paid"

5. Call liveauth_mcp_confirm with just the quoteId to receive the JWT

6. Use the JWT with either generic liveauth_mcp_charge metering or SDK paid-tool attribution

Authentication Flow

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│  AI Agent       │────▶│  MCP Server     │────▶│  LiveAuth API   │
│                 │     │                 │     │                 │
│ 1. Start       │     │ /api/mcp/start  │     │ Returns PoW    │
│ 2. Solve PoW   │     │                 │     │ challenge       │
│ 3. Confirm     │     │ /api/mcp/confirm│     │ Returns JWT    │
│ 4. API calls   │     │                 │     │                 │
│ 5. Charge      │     │ /api/mcp/charge │     │ Meter usage    │
└─────────────────┘     └─────────────────┘     └─────────────────┘

Paid tool servers use the same JWT but charge through an attributed endpoint:

Agent calls MCP tool
→ Tool server calls POST /api/mcp/tools/{toolId}/charge
  or POST /api/mcp/charge with toolName
→ LiveAuth validates JWT and budget
→ LiveAuth records gross / platform fee / net revenue and returns a signed receipt
→ Tool handler runs and returns the result

L402 Bundle Flow

LiveAuthCore supports Lightning-backed L402 bundles for prepaid MCP access. Buy a bundle, claim the macaroon after payment, then start an MCP session in L402 mode and confirm it with that macaroon.

# 1. Create a bundle invoice.
curl -X POST https://api.liveauth.app/api/public/l402/bundle/invoice \
  -H "Content-Type: application/json" \
  -d '{"publicKey":"la_pk_xxx","tier":"starter","agentId":"agent_abc"}'

# 2. After the invoice is paid, claim a macaroon.
curl -X POST https://api.liveauth.app/api/public/l402/bundle/claim \
  -H "Content-Type: application/json" \
  -d '{"publicKey":"la_pk_xxx","paymentHash":"payment_hash_from_step_1"}'

# 3. Start and confirm an MCP session with the macaroon.
curl -X POST https://api.liveauth.app/api/mcp/start \
  -H "X-LW-Public: la_pk_xxx" \
  -H "Content-Type: application/json" \
  -d '{"forceL402":true}'

curl -X POST https://api.liveauth.app/api/mcp/confirm \
  -H "X-LW-Public: la_pk_xxx" \
  -H "Content-Type: application/json" \
  -d '{"quoteId":"quote_id_from_step_3","macaroon":"macaroon_from_step_2"}'

Development

# Install dependencies
npm install

# Build
npm run build

# Run locally
node dist/cli.js

Resources

• LiveAuth Demo & Docs

• MCP Protocol Spec

• GitHub Repository

License

MIT

Categories: authentication · payments · lightning · l402 · bitcoin · pay-per-call · metering · agent-tools · anti-abuse · mcp-server · typescript