Eraser API + MCP vs tldraw SDK + MCP

Eraser API + MCP

Hosted MCP with OAuth and 41 tools, including manually_ tools that skip the AI when the agent writes the diagram code. No status page, rate limits, SLA or changelog.

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.

Eraser API + MCP

1. Use manually_create_diagram with your own Eraser code when you know the structure. It skips the AI and its credits
2. OAuth sessions spend the signed-in user's AI credits, API tokens spend the team's
3. Call /render/elements ($0.20) when you already have diagram code; /render/prompt costs $0.80
4. Set a spend limit before running in CI. At 100 per cent the API stops until the next calendar month

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