AI agents use spline_place_props to create or update resources in Uefn — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Uefn environment.
Based on the name, this tool likely places (creates) prop actors along a spline path in the live Unreal Editor for Fortnite scene. Placing objects is a Write operation — it creates new data in the scene. Since descriptions are empty, confidence is reduced, but the sibling tools (actor_place, audio_place patterns) and the 'place' verb support the Write classification.
From the tool's definition Tool name 'spline_place_props' suggests placing props along a spline in the UEFN editor — a Write (create/modify) operation. Description is empty, lowering confidence.
Documented attack patterns abuse exactly the kind of access spline_place_props gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Uefn, and nothing reaches the server without passing your rules. This is the rule we recommend for spline_place_props:
{
"version": "1",
"default": "deny",
"tools": {
"spline_place_props": {
"limits": [
{
"counter": "spline_place_props_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}spline_place_props 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.
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spline_place_props. It is categorised as a Write tool in the Uefn MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Uefn MCP server in PolicyLayer and add a rule for spline_place_props: 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 Uefn. Nothing to install.
spline_place_props 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 spline_place_props 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 spline_place_props. 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.
spline_place_props is provided by the Uefn MCP server (quangdang46/uefn-verse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Uefn, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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143 Uefn tools catalogued and risk-classified — across an index of 43,000+ MCP servers.