call_preset_function · Unreal MCP: Risk & Policy

WHAT IT DOES

What call_preset_function does on Unreal

AI agents invoke call_preset_function to trigger actions in Unreal. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why call_preset_function needs a policy

This tool executes functions exposed through Unreal Engine's Remote Control Preset system. Since it calls arbitrary functions, the effects are entirely dependent on what function is invoked — could range from benign reads to destructive operations. The most severe applicable category is Execute, as it triggers external operations whose effects depend on arguments.

From the tool's definition "Call a function exposed via a Remote Control Preset"

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

call_preset_function Rate-limited

call_preset_function stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "call_preset_function": {
      "limits": [
        {
          "counter": "call_preset_function_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-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 call_preset_function

What does the call_preset_function tool do? +

Call a function exposed via a Remote Control Preset. It is categorised as a Execute tool in the Unreal MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on call_preset_function? +

Register the Unreal MCP server in PolicyLayer and add a rule for call_preset_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 call_preset_function? +

call_preset_function is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit call_preset_function? +

Yes. Add a rate_limit block to the call_preset_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 call_preset_function completely? +

Set action: deny in the PolicyLayer policy for call_preset_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 call_preset_function? +

call_preset_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.