draw.io + MCP vs tldraw SDK + MCP

draw.io + MCP

Free, keyless and Apache 2.0, with a Docker image for self-hosting. Tool descriptions embed a 34.5 KB XML reference and a 14 KB Mermaid reference, roughly 13,000 tokens.

tldraw SDK + MCP

Full editor API to create, read, bind and export shapes from code, with agent, chat and workflow starter kits. Source-available, and commercial prices aren't published.

draw.io + MCP

1. Pass mermaid to create_diagram for any type on its Mermaid list. Use xml only for icons, mockups or hand-placed layouts
2. Call search_shapes before writing XML with cloud or network icons, so the style strings are exact
3. Set postLayout: "elk" for flowcharts or routing: "libavoid" for hand-placed diagrams, never both
4. Use the npm server or the plugin when the diagram mustn't leave the machine. The hosted App sends it to draw.io's server
5. Expect the tool list to cost about 13,000 tokens before the first call

tldraw SDK + MCP

1. Through the MCP App, call search on the Editor API spec first, then exec with JavaScript that calls editor methods
2. Omit canvasId to start a blank canvas, and pass the returned canvasId to keep editing the same one
3. Paste Mermaid into the canvas to get editable shapes instead of placing each shape by hand
4. Return editor.getCurrentPageShapes() from exec to check what was drawn
5. Read the release notes before a minor upgrade. Minor versions can break