AI can generate mermaid diagrams, not excalidraw. If you use the mermaid to excalidraw, i guess it can be, but it just looks like a mermaid diagram then and not an excalidraw.

PlantUML is a better ask for LLMs, you have a lot more control over the output

https://claude.com/connectors/excalidraw-app-demo

we have an excalidraw MCP for claude, it can easily do both :) (Excalidraw is basically just fancy SVG)