set_niagara_float · Unreal MCP: Risk & Policy

WHAT IT DOES

What set_niagara_float does on Unreal

AI agents use set_niagara_float 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_niagara_float needs a policy

This tool creates or modifies data (Niagara float parameters) in a reversible manner. While it affects visual effects rendering, parameter changes are not destructive—they can be undone by setting alternative values. The blast radius is medium: an AI agent could produce unintended visual effects, performance issues, or confusing VFX behavior, but cannot permanently delete assets or execute arbitrary code.

From the tool's definition Tool name 'set_niagara_float' and description 'Set a float parameter on a Niagara component' indicate modification of Niagara (VFX system) parameters. The verb 'set' modifies component state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_niagara_float Rate-limited

set_niagara_float 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_niagara_float": {
      "limits": [
        {
          "counter": "set_niagara_float_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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_niagara_float

What does the set_niagara_float tool do? +

Set a float parameter on a Niagara component. 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_niagara_float? +

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

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

Can I rate-limit set_niagara_float? +

Yes. Add a rate_limit block to the set_niagara_float 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_niagara_float completely? +

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

set_niagara_float 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.