When you go to the site, you're redirected to a URL like https://mcp.christmas/jolly-santa and anything you POST to that (e.g. curl https://mcp.christmas/jolly-santa -d "Hello World!") is delivered as an in-game notification (powered by cloudflare workers).
More detailed setup instruction at mcp.christmas, but the simple API makes this very easy to integrate with claude code stop hooks (which are deterministic), but you can also use MCP – though whether or not the notify_user tool is called depends on your model and harness and can be very unreliable (through no fault of the protocol).
Enjoy! Merry Christmas
nikhonit•2h ago