Aymeric Rabot and Wassim Samad created Pascal Editor, a free, open-source (MIT license) 3D building editor that runs in a browser tab with no sign-up required. Users draw walls with a mouse, and parametric doors and windows automatically create cutouts via boolean geometry using three-bvh-csg. Rendering uses Three.js in WebGPU, scenes save locally in IndexedDB, and history goes back 50 steps. The project offers @pascal-app/mcp on npm, a Model Context Protocol server that exposes the 3D scene to an agent, hooking Claude Desktop, Claude Code, Cursor or Codex into a floor plan. This provides around thirty tools usable in natural language, including create_room, add_door, add_window, furnish_room, measure, check_collisions, and undo. Three prompts are included, such as from_brief which turns a phrase like "a 2-room apartment in 80 m²" into modifications. Two tools read images—one for scanned floor plans, one for room photos—using the protocol's sampling capability. The server writes to a local SQLite database, and the editor page subscribes to the event stream, allowing walls to appear in real time as the agent works. A converter handles IFC files, and exports come out as GLB, STL or OBJ. A plugin system lets users add their own object types.