tldraw MCP in Claude: setup, a real run, and what the API can’t show

Claude Code. Add it over HTTP, then run /mcp to check that it connected:

claude mcp add --transport http tldraw https://tldraw-mcp-app.tldraw.workers.dev/mcp

It will connect, but read the test below first: a terminal can't show the canvas, and without it we got nothing back. If you want diagrams as files from Claude Code, the AndresMuelas2004 server writes .tldr files. Its README installs it from source:

git clone https://github.com/AndresMuelas2004/tldraw-mcp-server.git
cd tldraw-mcp-server && npm install && npm run build

then points Claude Code or Claude Desktop at node /path/to/tldraw-mcp-server/dist/index.js. The Mihai-Codes server adds a canvas you open in the browser (npm run canvas). Clone it from that URL; the clone link in its README returned a 404 when we checked.

Cursor. tldraw launched the app in Cursor first. In Settings › MCP, add a new global MCP server:

{
  "mcpServers": {
    "tldraw": { "url": "https://tldraw-mcp-app.tldraw.workers.dev/mcp" }
  }
}

ChatGPT and Codex. tldraw publishes a plugin for both. Open its page and choose Install plugin. Its listing says it can draw diagrams, wireframes and data, mark up screenshots, and link work to tldraw.com files, and that it may share relevant chats and memories with tldraw.

On 7 October 2026 we sent one prompt to Claude Sonnet 5.5 through the Claude API, connected to https://tldraw-mcp-app.tldraw.workers.dev/mcp. We reused the prompt from our Excalidraw test word for word, including the last sentence, which asks for something tldraw can't do:

Draw a diagram of how a RAG pipeline answers a question: user question, embed the question, vector search, top-k chunks, prompt with context, LLM answer. Then export it to excalidraw.com and give me the link.

Claude called three tools, in this order:

1. search, with code that pulled the helper functions and the rectangle and arrow shape specs: a 6,839-character answer.
2. exec, with JavaScript that placed six coloured boxes in two rows of three, a title, a "Vector database" box to the side, and arrows between the steps. The server replied only that the canvas "is rendering and your code is executing", and that the canvas state would be attached to the conversation shortly.
3. exec again, to read back every shape's position and check the layout. It got the same "is rendering" reply and no shapes.

Claude's answer, shortened:

I drew the RAG diagram, but I can't give you an excalidraw.com link. My tools only reach the tldraw canvas… and a link I made up wouldn't work. I haven't looked at the rendered canvas, so I can't promise the layout is free of overlaps.

What the run tells you:

• The canvas view is the whole product. The state comes back through tools that only the view calls, so through the API there was no drawing, no link and nothing to screenshot. Our reading of the server's reply is that the code runs inside the view itself. We expect the same in any client that can't show MCP Apps, but tested only the API.
• It is light on tokens. 20,144 input tokens against 53,557 for the same diagram with Excalidraw, because search returns only the parts of the API Claude asks for instead of a full format guide.
• Claude didn't bluff. It said it couldn't export, didn't invent a link, and said it hadn't seen the result.
• We didn't test the view inside the Claude app. That is why this page has no screenshot of the canvas.

Most drawing servers give Claude one tool per action: add a box, add an arrow. tldraw gives it two. search lets Claude write a little JavaScript that looks things up in the tldraw Editor API spec, and exec runs JavaScript on the canvas with the live editor. Whatever the editor can do, Claude can do, one shape at a time.

Four more tools are marked for the app only, so the canvas view calls them, not Claude: _exec_callback, _get_canvas_state, save_checkpoint and read_checkpoint. That is how the drawing and your own edits get back into the conversation.

This is newer than most write-ups. tldraw's launch post from March, its tools page and Claude's directory listing still describe diagram_drawing_read_me, create_shapes, update_shapes and delete_shapes. The live server we queried on 6 and 7 October 2026 had switched to search and exec. It identifies itself as "tldraw Canvas" 1.0.0, "an interactive tldraw canvas with tools for diagramming, drawing, and more".