clear_canvas

THE RISK

Critical Risk

This tool performs an irreversible bulk deletion operation that removes all elements from the canvas in a single action. While the action can theoretically be undone via undo functionality in Excalidraw itself, the tool as exposed through the MCP API performs a destructive operation with broad impact.

From the tool's definition Tool name 'clear_canvas' with description 'Clear all elements from the canvas' indicates irreversible deletion of all diagram content without the ability to selectively recover individual elements.

Risk signalsBulk/mass operation — affects multiple targets

Documented attack patterns abuse exactly the kind of access clear_canvas gives an agent:

HOW TO CONTROL CLEAR_CANVAS

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 clear_canvas:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "clear_canvas"
  ]
}

clear_canvas disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

Create a free account and register Excalidraw MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

More Excalidraw MCP Server tools

Destructive delete_element Delete an Excalidraw element Execute set_viewport Control the canvas viewport (camera). Auto-fit all elements, center on a specific element, Write snapshot_scene Save a named snapshot of the current canvas state for later restoration Write align_elements Align elements to a specific position Write batch_create_elements Create multiple Excalidraw elements at once. For arrows, use startElementId/endElementId t Write create_element Create a new Excalidraw element. For arrows, use startElementId/endElementId to bind to sh Write create_from_mermaid Convert a Mermaid diagram to Excalidraw elements and render them on the canvas Write distribute_elements Distribute elements evenly

All 26 Excalidraw MCP Server tools →

Destructive tools on other servers

Frida Game Hacking MCP clear_scan MegaMemory remove_concept Frida Agent MCP kill_app 1MCP Server mcp_uninstall

Go deeper

Critical-risk tools in Excalidraw MCP Server → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

What does the clear_canvas tool do? +

Clear all elements from the canvas. It is categorised as a Destructive tool in the Excalidraw MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on clear_canvas? +

Register the Excalidraw MCP Server MCP server in PolicyLayer and add a rule for clear_canvas: 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.

What risk level is clear_canvas? +

clear_canvas is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit clear_canvas? +

Yes. Add a rate_limit block to the clear_canvas 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.

How do I block clear_canvas completely? +

Set action: deny in the PolicyLayer policy for clear_canvas. 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.

What MCP server provides clear_canvas? +

clear_canvas 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.

Enforce policy on every Excalidraw MCP Server tool call.

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.

// WHAT CLEAR_CANVAS ON EXCALIDRAW MCP SERVER DOES

// THE RISK

// HOW TO CONTROL CLEAR_CANVAS

// EXPLORE