Take a screenshot of the current canvas and return it as an image. Requires the canvas frontend to be open in a browser. Use this to visually verify what the diagram looks like.
AI agents call get_canvas_screenshot to retrieve information from Excalidraw MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
get_canvas_screenshot is a read-only operation that captures and returns the current state of the canvas as an image. It has no side effects, does not modify any data, and does not execute code or commands. It is purely a retrieval operation for viewing purposes, making it a Read category tool with low severity.
From the tool's definition Tool name and description: 'Take a screenshot of the current canvas and return it as an image.' This retrieves a visual representation of the canvas without modifying, deleting, or executing any operations that affect the diagram data.
Documented attack patterns abuse exactly the kind of access get_canvas_screenshot gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Excalidraw MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_canvas_screenshot:
{
"version": "1",
"default": "deny",
"tools": {
"get_canvas_screenshot": {}
}
}get_canvas_screenshot is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Take a screenshot of the current canvas and return it as an image. Requires the canvas frontend to be open in a browser. Use this to visually verify what the diagram looks like. It is categorised as a Read tool in the Excalidraw MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Excalidraw MCP Server MCP server in PolicyLayer and add a rule for get_canvas_screenshot: 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 Excalidraw MCP Server. Nothing to install.
get_canvas_screenshot 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 get_canvas_screenshot 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 get_canvas_screenshot. 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.
get_canvas_screenshot is provided by the Excalidraw MCP Server MCP server (yctimlin/mcp_excalidraw). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 26 Excalidraw MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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26 Excalidraw MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.