layer_set · Open Brush MCP Server MCP: Risk & Policy

WHAT IT DOES

What layer_set does on Open Brush MCP Server

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

WHY IT NEEDS A POLICY

Why layer_set needs a policy

Setting an active layer is a reversible modification operation that changes application state but does not delete data or execute arbitrary code. It falls under Write category as it modifies the painting document's layer structure. Severity is medium because misuse could cause confusion or unintended edits to wrong layers, but changes can be undone in a drawing application.

From the tool's definition Tool name is 'layer_set' and description states it 'Sets active layer', which modifies the state of the 3D painting application by changing which layer is active.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

layer_set Rate-limited

layer_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": {
    "layer_set": {
      "limits": [
        {
          "counter": "layer_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 Open Brush MCP Server, so you can run agents against it safely.

FAQ

Questions about layer_set

What does the layer_set tool do? +

Sets active layer. It is categorised as a Write tool in the Open Brush MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on layer_set? +

Register the Open Brush MCP Server MCP server in PolicyLayer and add a rule for layer_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 Open Brush MCP Server. Nothing to install.

What risk level is layer_set? +

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

Can I rate-limit layer_set? +

Yes. Add a rate_limit block to the layer_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 layer_set completely? +

Set action: deny in the PolicyLayer policy for layer_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 layer_set? +

layer_set is provided by the Open Brush MCP Server MCP server (moz411/openbrush-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.