AI agents invoke select_actors 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.
Selecting actors triggers an editor UI action/operation in Unreal Engine — it changes the editor's selection state, which is an external operation with side effects (e.g., affecting subsequent editor commands). It doesn't read data passively, nor does it write/create/modify scene content, but it does trigger an editor interaction.
From the tool's definition Select one or more actors in the Unreal Editor
Documented attack patterns abuse exactly the kind of access select_actors gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Unreal, and nothing reaches the server without passing your rules. This is the rule we recommend for select_actors:
{
"version": "1",
"default": "deny",
"tools": {
"select_actors": {
"limits": [
{
"counter": "select_actors_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}select_actors 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.
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Select one or more actors in the Unreal Editor. 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.
Register the Unreal MCP server in PolicyLayer and add a rule for select_actors: 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.
select_actors 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 select_actors 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 select_actors. 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.
select_actors is provided by the Unreal MCP server (runeape-sats/unreal-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 21 Unreal tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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21 Unreal tools catalogued and risk-classified — across an index of 42,500+ MCP servers.