build_target
Build a C++ target using UnrealBuildTool. Compiles the project's C++ code.
This record as markdown: /tools/jjpxdev-unreal-mcp/build-target.md
What build_target does on Unreal
AI agents invoke build_target 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 |
|---|---|---|---|
clean | boolean | — | Clean build |
target | string | — | Build target: Editor, Game, Client, Server |
platform | object | — | Target platform (default from config, e.g., Win64) |
configuration | object | — | Build config: Debug, DebugGame, Development, Shipping, Test |
Parameters from the server's own tool schema.
Why build_target is rated High
build_target triggers real processes with real consequences. An agent gone sideways doesn't fire it once. It starts dozens of builds, sends mass notifications, or burns through compute before anyone looks up.
Attacks that exploit this kind of access
The rule that runs build_target 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 build_target, this is the rule to start with:
build_target 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 build_target call is checked against it from then on.
Questions about build_target
Build a C++ target using UnrealBuildTool. Compiles the project's C++ code. 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.
build_target accepts 4 parameters: clean, target, platform, configuration. 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 build_target: 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.
build_target 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 build_target 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 build_target. 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.
build_target 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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