palette_set · Whiteboard MCP: Risk & Policy

WHAT IT DOES

What palette_set does on Whiteboard

AI agents use palette_set 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 palette_set needs a policy

This tool modifies the color palette of an Excalidraw diagram by adding or updating color entries. It is a reversible write operation (colors can be changed or removed later) with minimal blast radius - color palette changes do not affect critical data, financial systems, or enable execution of external commands.

From the tool's definition Tool description states "Merge entries into the workspace color palette" - a modification operation. The term "Merge" indicates data is being created or modified within the palette state, not retrieved or deleted.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

palette_set Rate-limited

palette_set 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": {
    "palette_set": {
      "limits": [
        {
          "counter": "palette_set_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 palette_set

What does the palette_set tool do? +

Merge entries into the workspace color palette and return the resulting palette. 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 palette_set? +

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

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

Can I rate-limit palette_set? +

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

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

palette_set 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.