start_trace · Unreal MCP: Risk & Policy

WHAT IT DOES

What start_trace does on Unreal

AI agents invoke start_trace 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 start_trace needs a policy

This tool executes a profiling/tracing operation in Unreal Engine, which is an external system action. While not destructive or permanently modifying data, trace sessions consume resources and affect system state during their execution. The action is triggered by the tool call and its effects depend on parameters (selected channels).

From the tool's definition Tool name is 'start_trace' and description states it 'Start[s] an Unreal Insights trace session with selected channels.' Starting a trace session triggers external profiling/monitoring operations whose runtime behavior and resource consumption depend on…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_trace Rate-limited

start_trace 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": {
    "start_trace": {
      "limits": [
        {
          "counter": "start_trace_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 start_trace

What does the start_trace tool do? +

Start an Unreal Insights trace session with selected channels. 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 start_trace? +

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

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

Can I rate-limit start_trace? +

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

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

start_trace 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.