set_niagara_color
Set a linear color parameter on a Niagara component.
This record as markdown: /tools/jjpxdev-unreal-mcp/set-niagara-color.md
What set_niagara_color does on Unreal
AI agents use set_niagara_color 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 |
|---|---|---|---|
value | object | Yes | RGBA color (0-1) |
actor_name | string | Yes | Actor with Niagara component |
parameter_name | string | Yes | Parameter name |
Parameters from the server's own tool schema.
Why set_niagara_color is rated Medium
This tool modifies visual/rendering properties of a Niagara particle system by setting a color parameter. This is a reversible change to component state—the parameter can be changed back or reset. It does not delete data (Destructive), execute arbitrary code (Execute), involve financial transactions (Financial), or create new assets (though it does modify existing ones).
From the tool's definition Tool name indicates a parameter modification action: 'set_niagara_color' modifies a visual property on a Niagara component (a particle system in Unreal Engine).
Attacks that exploit this kind of access
The rule that runs set_niagara_color 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 set_niagara_color, this is the rule to start with:
set_niagara_color 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 set_niagara_color call is checked against it from then on.
Questions about set_niagara_color
Set a linear color 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.
set_niagara_color accepts 3 parameters: value, actor_name, parameter_name. Required: value, actor_name, parameter_name. 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 set_niagara_color: 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.
set_niagara_color 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 set_niagara_color 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 set_niagara_color. 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.
set_niagara_color 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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