compile_blueprint · Unreal MCP: Risk & Policy

WHAT IT DOES

What compile_blueprint does on Unreal

AI agents invoke compile_blueprint 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 compile_blueprint needs a policy

Compiling a Blueprint executes the Unreal Engine's blueprint compiler, which processes and transforms blueprint logic into executable form. This is an Execute action rather than a simple Write because it triggers an external process (the compiler) whose effects depend on the blueprint's content and current state.

From the tool's definition Tool name 'compile_blueprint' and description 'Compile a Blueprint' indicate execution of a compilation process on Unreal Engine assets. Compilation is a code execution operation that transforms Blueprint source into compiled bytecode.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

compile_blueprint Rate-limited

compile_blueprint 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": {
    "compile_blueprint": {
      "limits": [
        {
          "counter": "compile_blueprint_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 compile_blueprint

What does the compile_blueprint tool do? +

Compile a Blueprint. 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 compile_blueprint? +

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

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

Can I rate-limit compile_blueprint? +

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

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

compile_blueprint 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.