Export the canvas as a standard Excalidraw JSON (.excalidraw) file that can be opened in the Excalidraw desktop app, excalidraw.com, or any tool reading the official schema. Our internal custom fields (parentId / relX / relY) are resolved into absolute x/y and stripped by default.
AI agents call canvas_export_json to retrieve information from Whiteboard without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool reads/exports the current canvas state as a JSON file. It performs no modifications, deletions, or external operations — it simply serializes and outputs the canvas data. The mention of resolving custom fields into absolute coordinates is a read-time transformation, not a write operation.
From the tool's definition Export the canvas as a standard Excalidraw JSON (.excalidraw) file
Attacks that exploit this kind of access
Export the canvas as a standard Excalidraw JSON (.excalidraw) file that can be opened in the Excalidraw desktop app, excalidraw.com, or any tool reading the official schema. Our internal custom fields (parentId / relX / relY) are resolved into absolute x/y and stripped by default. It is categorised as a Read tool in the Whiteboard MCP Server, which means it retrieves data without modifying state.
Register the Whiteboard MCP server in PolicyLayer and add a rule for canvas_export_json: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Whiteboard. Nothing to install.
canvas_export_json is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the canvas_export_json rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for canvas_export_json. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
canvas_export_json is provided by the Whiteboard MCP server (kamiazya/whiteboard). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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