spawn_niagara_attached
Spawn a Niagara system attached to an actor.
This record as markdown: /tools/jjpxdev-unreal-mcp/spawn-niagara-attached.md
What spawn_niagara_attached does on Unreal
AI agents invoke spawn_niagara_attached 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.
| Parameter | Type | Required | Description |
|---|---|---|---|
actor_name | string | Yes | Actor name or label to attach to |
system_path | string | Yes | Niagara system asset path |
Parameters from the server's own tool schema.
Why spawn_niagara_attached is rated High
This tool spawns (instantiates and runs) a Niagara particle system attached to an existing actor in the Unreal Engine scene. It triggers an external operation within the engine that creates a runtime object and initiates simulation. It's not purely a write (data creation) but an execution of a live system component.
From the tool's definition Spawn a Niagara system attached to an actor
Attacks that exploit this kind of access
The rule that runs spawn_niagara_attached 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_niagara_attached, this is the rule to start with:
spawn_niagara_attached 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Unreal, apply this rule, and every spawn_niagara_attached call is checked against it from then on.
Questions about spawn_niagara_attached
Spawn a Niagara system attached to an actor. 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.
spawn_niagara_attached accepts 2 parameters: actor_name, system_path. Required: actor_name, system_path. 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_niagara_attached: 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_niagara_attached is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the spawn_niagara_attached 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_niagara_attached. 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_niagara_attached 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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