Demo MCP server showing spawnpay-paywall in action. One tool: fetch_tweet. Each call charges the agent $0.001 USDC, sends it to the author's spawnpay wallet.

Why this exists

To prove an MCP author can charge per call without forcing users to handle credit cards. ~30 lines of real logic + 1 paywall wrapper.

Run it

{
  "mcpServers": {
    "spawnpay": { "command": "npx", "args": ["-y", "spawnpay-mcp"] },
    "tweet-fetcher": {
      "command": "node",
      "args": ["/path/to/tweet-fetcher-mcp/src/index.js"],
      "env": { "SPAWNPAY_API_KEY": "spk_caller_key_here" }
    }
  }
}

Then:

Use fetch_tweet on https://x.com/elonmusk/status/...

Each call costs the caller $0.001. The author keeps $0.000995. Spawnpay takes 0.5%.

How it's wired

import { paywall } from 'spawnpay-paywall';

const fetchTweet = paywall(
  { price: 0.001, vendor: 'SP_yourCode', description: 'fetch_tweet' },
  fetchTweetImpl,
);