update_element · Whiteboard MCP: Risk & Policy

WHAT IT DOES

What update_element does on Whiteboard

AI agents use update_element to create or update resources in Whiteboard — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Whiteboard environment.

WHY IT NEEDS A POLICY

Why update_element needs a policy

This tool creates or modifies data (the Excalidraw diagram) but does not delete, destroy, or execute arbitrary code. Changes are reversible — elements can be updated again or the canvas can be reset via canvas_clear. The blast radius is limited to the collaborative whiteboard canvas itself, affecting only diagram annotations with no external side effects or data loss.

From the tool's definition The tool patches/modifies existing elements in-place, allowing changes to text, strokeColor, and positioning (x/y/width/height).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_element Rate-limited

update_element stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_element": {
      "limits": [
        {
          "counter": "update_element_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Whiteboard, so you can run agents against it safely.

FAQ

Questions about update_element

What does the update_element tool do? +

Patch fields of an existing element in-place (e.g., change text, strokeColor, x/y/width/height). Any Excalidraw element field can be set via patch. It is categorised as a Write tool in the Whiteboard MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_element? +

Register the Whiteboard MCP server in PolicyLayer and add a rule for update_element: 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.

What risk level is update_element? +

update_element is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit update_element? +

Yes. Add a rate_limit block to the update_element 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 update_element completely? +

Set action: deny in the PolicyLayer policy for update_element. 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 update_element? +

update_element 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.

// THE FULL RECORD

update_element is one line of Whiteboard's registry record.

The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.

Teams ship this data inside their own products. See what a licence covers →