what it is
A design canvas built for working with agents. You design on the canvas, refine by hand and ship the result back to code. It runs as a desktop app and an editor extension, and exposes an MCP server so a coding agent can read and edit its design files. pencil.dev has since rebranded to pen.dev.
how I use it
I tried it as an AI design tool, with Claude working on the canvas through its MCP server.