This is a full-featured toolkit for building Excalidraw diagrams programmatically through MCP tools or REST API. It handles the entire lifecycle: create elements, query and update them, export to PNG/SVG, save snapshots, convert Mermaid diagrams, and most importantly, lets agents iterate by taking screenshots of their own work to refine layouts. The source documentation is unusually thorough about coordinate systems, spacing rules, and common layout mistakes like putting labels on background zones or drawing arrows that cross through unrelated shapes. It requires running a local Express server on port 3000. If you need agents to draw architecture diagrams, flowcharts, or any visual explanation that benefits from programmatic layout and iterative refinement, this does the job.
npx skills add https://github.com/yctimlin/mcp_excalidraw --skill excalidraw-skill