Excalidraw MCP diagrams not rendering in Claude Code (desktop app)

Summary

The official Excalidraw MCP (mcp__a5ed4421-a39c-4118-abc9-ffc0850f24cf) is available as a platform-level MCP in Claude Code within the desktop app. Tool calls like create_view succeed and return valid checkpoint IDs, but the rendered Excalidraw diagram never appears inline in the Claude Code conversation.

Expected behavior

Excalidraw diagrams should render inline in Claude Code conversations within the desktop app, similar to how they render in Claude Cowork (see screenshot context below).

Actual behavior

• create_view returns a checkpoint ID (e.g., {"checkpointId":"a92d14dd33564edeba"}) — the server-side call succeeds
• No diagram is displayed inline in the Claude Code conversation
• The same Excalidraw MCP renders diagrams correctly in Claude Cowork within the same desktop app

Environment

• Platform: macOS (Darwin 25.1.0)
• Claude Code in the desktop app (not terminal CLI)
• claudemcpcontent.com does not resolve via DNS (nslookup, dig, curl all fail) — this may be the root cause if Claude Code relies on client-side DNS resolution for the rendering iframe, while Cowork resolves it server-side

Steps to reproduce

1. Open Claude Code in the desktop app
2. Call the Excalidraw MCP create_view tool with valid elements
3. Observe that a checkpoint ID is returned but no diagram is rendered

Workaround

Using a community Excalidraw MCP (yctimlin/mcp_excalidraw) with a local canvas server at localhost:3000 and pushing elements via HTTP API.