create_material_function · Unreal MCP: Risk & Policy

WHAT IT DOES

What create_material_function does on Unreal

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

WHY IT NEEDS A POLICY

Why create_material_function needs a policy

This tool creates new material functions, which are reversible asset modifications in Unreal Engine. It does not execute arbitrary code, delete assets, move money, or trigger external operations with unpredictable effects.

From the tool's definition Tool name is 'create_material_function' and description states 'Create a reusable material function.' The verb 'create' indicates data creation/modification within Unreal Engine's material system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_material_function Rate-limited

create_material_function 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": {
    "create_material_function": {
      "limits": [
        {
          "counter": "create_material_function_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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

FAQ

Questions about create_material_function

What does the create_material_function tool do? +

Create a reusable material function. It is categorised as a Write tool in the Unreal MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_material_function? +

Register the Unreal MCP server in PolicyLayer and add a rule for create_material_function: 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 Unreal. Nothing to install.

What risk level is create_material_function? +

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

Can I rate-limit create_material_function? +

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

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

create_material_function is provided by the Unreal MCP server (sam-david/unreal-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.