recompile_material · Unreal MCP: Risk & Policy

WHAT IT DOES

What recompile_material does on Unreal

AI agents invoke recompile_material 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 recompile_material needs a policy

Recompiling a material triggers an execution process (shader compilation) in Unreal Engine. It doesn't simply read or write data in a reversible way; it runs the material compiler pipeline. The blast radius is medium since a failed or corrupted recompile could break material rendering across the project, but it doesn't irreversibly delete data.

From the tool's definition 'Recompile a material after making changes to its graph' — triggers a compilation/build process on a material asset

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

recompile_material Rate-limited

recompile_material 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": {
    "recompile_material": {
      "limits": [
        {
          "counter": "recompile_material_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 recompile_material

What does the recompile_material tool do? +

Recompile a material after making changes to its graph. 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 recompile_material? +

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

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

Can I rate-limit recompile_material? +

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

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

recompile_material 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.