set_material_expression_property

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/set-material-expression-property.md

WHAT IT DOES

What set_material_expression_property does on Unreal-MCP

AI agents use set_material_expression_property 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 set_material_expression_property is rated Medium

The tool performs a 'set' operation on material expression properties, which is a reversible modification of editor state/assets. This is Write-category behavior. Severity is high because misuse could corrupt or deface materials/assets in a project, affecting visual output and requiring manual correction.

From the tool's definition Tool name 'set_material_expression_property' indicates modification of material expression properties in Unreal Engine 5.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs set_material_expression_property 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 set_material_expression_property, this is the rule to start with:

set_material_expression_property Rate-limited

set_material_expression_property 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": {
    "set_material_expression_property": {
      "limits": [
        {
          "counter": "set_material_expression_property_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 set_material_expression_property call is checked against it from then on.

FAQ

Questions about set_material_expression_property

What does the set_material_expression_property tool do? +

set_material_expression_property 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 set_material_expression_property? +

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

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

Can I rate-limit set_material_expression_property? +

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

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

set_material_expression_property 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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