create_material · Unreal MCP: Risk & Policy

WHAT IT DOES

What create_material does on Unreal

AI agents use create_material 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 needs a policy

Creating a material asset is a reversible write operation that adds new data to the Unreal Engine project. It does not execute arbitrary code, delete data, or perform financial transactions. The severity is medium because misuse could clutter the project or create unwanted assets, but the operation is reversible through standard asset deletion workflows.

From the tool's definition Tool description states 'Create a new material asset.' The verb 'create' and direct reference to asset creation indicates this tool modifies the project state by adding a new material asset.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_material Rate-limited

create_material 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": {
      "limits": [
        {
          "counter": "create_material_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 Unreal, so you can run agents against it safely.

FAQ

Questions about create_material

What does the create_material tool do? +

Create a new material asset. 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? +

Register the Unreal MCP server in PolicyLayer and add a rule for create_material: 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? +

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

Can I rate-limit create_material? +

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

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

create_material 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.