This record as markdown: /tools/jjpxdev-unreal-mcp/spawn-actor.md
What spawn_actor does on Unreal
AI agents use spawn_actor 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.
| Parameter | Type | Required | Description |
|---|---|---|---|
label | string | — | Actor label in the editor |
scale | object | — | Actor scale (default: 1,1,1) |
location | object | — | |
rotation | object | — | |
actor_class | string | Yes | Actor class to spawn (e.g., StaticMeshActor, PointLight, CameraActor) |
Parameters from the server's own tool schema.
Why spawn_actor is rated Medium
Spawning an actor creates a new object in the scene, which is a reversible write operation (the actor can be deleted afterward). It does not execute code, delete anything, or involve financial transactions.
From the tool's definition Spawn a new actor in the current level
Risk signalsHigh parameter count (14 properties)
Attacks that exploit this kind of access
The rule that runs spawn_actor safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Unreal, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For spawn_actor, this is the rule to start with:
spawn_actor 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Unreal, apply this rule, and every spawn_actor call is checked against it from then on.
Questions about spawn_actor
Spawn a new actor in the current level. 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.
spawn_actor accepts 5 parameters: label, scale, location, rotation, actor_class. Required: actor_class. The full parameter table on this page comes from the server's own tool schema.
Register the Unreal MCP server in PolicyLayer and add a rule for spawn_actor: 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.
spawn_actor is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the spawn_actor 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.
Set action: deny in the PolicyLayer policy for spawn_actor. 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.
spawn_actor is provided by the Unreal MCP server (@jjpxdev/unreal-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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