https://github.com/caffeinum/tracepaper

I was frustrated that paper.design charges for the usage (!) of their MCP, so built open-source alternative.

It's a canvas for agents, where they can push mock designs, instead of having html files flying around across multiple tabs

You can leave comments to the agent at the same canvas. And there's a share mode that uses cloudflare tunnels

https://github.com/caffeinum/tracepaper