create_material_instance

A write tool on the Unreal- MCP server.

SERVERUnreal-MCP SOURCEaadeshrao123/unreal-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/aadeshrao123-unreal-mcp/create-material-instance.md

WHAT IT DOES

What create_material_instance does on Unreal-MCP

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

RISK

Why create_material_instance is rated Medium

Creating a material instance is a reversible modification to the project (assets can be deleted), not a destructive permanent loss of data. It does not execute arbitrary code, delete irreversibly, or involve financial transactions. The severity is medium because misuse could clutter the project with unwanted assets, but the operation is undoable.

From the tool's definition Tool name 'create_material_instance' indicates creation of a new material instance asset in Unreal Engine 5. This is a reversible write operation.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs create_material_instance safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Unreal-MCP, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For create_material_instance, this is the rule to start with:

create_material_instance Rate-limited

create_material_instance 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_instance": {
      "limits": [
        {
          "counter": "create_material_instance_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Unreal-MCP, apply this rule, and every create_material_instance call is checked against it from then on.

FAQ

Questions about create_material_instance

What does the create_material_instance tool do? +

create_material_instance is a write tool on the Unreal MCP server. It is categorised as a Write tool in the Unreal-MCP 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_instance? +

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

What risk level is create_material_instance? +

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

Can I rate-limit create_material_instance? +

Yes. Add a rate_limit block to the create_material_instance 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_instance completely? +

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

create_material_instance is provided by the Unreal MCP server (aadeshrao123/unreal-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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