update_frame_members · Whiteboard MCP: Risk & Policy

WHAT IT DOES

What update_frame_members does on Whiteboard

AI agents use update_frame_members 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_frame_members needs a policy

This tool performs create/update operations on diagram elements—specifically modifying frame contents and recomputing frame dimensions. While it doesn't delete data or execute arbitrary code, it does alter the diagram state in ways that affect rendering and exports. The 'all-or-nothing' atomicity and computed geometry suggest transactional semantics typical of Write operations.

From the tool's definition The tool "Add/remove elements from an existing frame" directly modifies an existing frame's membership and geometry properties (frameId, x/y/width/height). This is a reversible state change to the diagram structure.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_frame_members Rate-limited

update_frame_members 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_frame_members": {
      "limits": [
        {
          "counter": "update_frame_members_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_frame_members

What does the update_frame_members tool do? +

Add/remove elements from an existing frame without recreating it (frameId stays stable so export_png({frameId}) still targets the same group). All-or-nothing on missing ids. Recomputes frame x/y/width/height from the final member bbox plus padding. 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_frame_members? +

Register the Whiteboard MCP server in PolicyLayer and add a rule for update_frame_members: 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_frame_members? +

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

Can I rate-limit update_frame_members? +

Yes. Add a rate_limit block to the update_frame_members 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_frame_members completely? +

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

update_frame_members 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.