set_blueprint_property · Unreal MCP: Risk & Policy

WHAT IT DOES

What set_blueprint_property does on Unreal

AI agents use set_blueprint_property to create or update resources in Unreal — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Unreal environment.

WHY IT NEEDS A POLICY

Why set_blueprint_property needs a policy

This tool modifies Blueprint properties but does not delete data or execute arbitrary code—it sets configuration values. While it could affect game behavior if misused, the operation is reversible (properties can be changed back). The blast radius is contained to the specific Blueprint being modified, making it Write severity medium rather than higher categories.

From the tool's definition Tool name 'set_blueprint_property' and description 'Set a default property value on a Blueprint' indicate modification of Blueprint configuration properties. This is a reversible write operation that changes data within Unreal Engine's visual scripting system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_blueprint_property Rate-limited

set_blueprint_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_blueprint_property": {
      "limits": [
        {
          "counter": "set_blueprint_property_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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 set_blueprint_property

What does the set_blueprint_property tool do? +

Set a default property value on a Blueprint. It is categorised as a Write tool in the Unreal 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_blueprint_property? +

Register the Unreal MCP server in PolicyLayer and add a rule for set_blueprint_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. Nothing to install.

What risk level is set_blueprint_property? +

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

Can I rate-limit set_blueprint_property? +

Yes. Add a rate_limit block to the set_blueprint_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_blueprint_property completely? +

Set action: deny in the PolicyLayer policy for set_blueprint_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_blueprint_property? +

set_blueprint_property 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.