ue-mcp-workflow

Use when driving Unreal Engine editor via the ue-mcp MCP server. Covers the required order of operations (status check first), editor lifecycle, project scoping, and what to do when the bridge says "still initializing". Pulls in automatically any time the user asks to use an Unreal project or references ue-mcp tools.

ue-mcp workflow

The ue-mcp MCP exposes 19 category tools (action-dispatch style) that drive a live Unreal Engine editor via a C++ bridge plugin. Every tool takes an action parameter.

Start every session with a status check

Always call project(action="get_status") before anything else. It tells you:

  • Whether the bridge is connected
  • Which project is loaded
  • Whether the editor is responsive

If status reports not connected / editor not running, call editor(action="start_editor") to launch UE. Wait for the status check to succeed before issuing other calls — handlers that need the editor world will return "Editor is still initializing. Please wait and retry." if you call them too early.

Orient yourself before authoring

Before writing, read. Common orientation calls:

  • level(action="get_outliner") — what's in the current level
  • asset(action="list", directory="/Game/...", recursive=true) — what assets exist
  • asset(action="search_fts", query="...") — ranked search across names/classes/paths (after asset(action="reindex_fts") has built the index)
  • reflection(action="reflect_class", className="StaticMeshActor") — inspect any UE class
  • project(action="list_project_modules") — native C++ modules in the project

Mutation recipe

For any write action:

  1. Call the read/list variant first to confirm the target exists and capture the current shape (e.g. blueprint(action="read", assetPath=...) before add_node).
  2. Issue the write. Most write handlers return { success, existed, created, updated, rollback? } — honor existed as "idempotent no-op" and updated as "real change made".
  3. If a rollback record came back and you hit a later failure in the same logical unit, call the rollback method yourself (the TS flow runner does this automatically when tasks are composed via ue-mcp.yml).

Common pitfalls

  • Action typos silently fail — each tool validates action against an enum; a typo returns Unknown action '<x>'. Available: <list>. Read the Available: list rather than guessing.
  • Asset paths use /Game/..., not filesystem paths. Package paths (folder) vs object paths (Folder/Name.Name) matter — most create handlers take packagePath (folder) plus name; most read handlers take assetPath (full object path).
  • execute_python is an escape hatch, not a shortcut — if a native tool exists for the job, use it. When you use execute_python, a hook may prompt you to file a GitHub issue so the native tool gap can be closed.
  • Editor must be fully loaded for asset registry queries. If a list_* action retries with "still initializing", the editor is still starting — wait a few seconds and retry.

When something truly can't be done

If no native action covers your case:

  1. Try reflection(action="search_classes"/"search_functions", query=...) to confirm no UFUNCTION exists.
  2. Use execute_python as a last resort.
  3. Consider using feedback to open a GitHub issue against db-lyon/ue-mcp describing the gap.