Automation surface selector

Task shape	Choose	Notes
Right-click selected assets/actors	Scripted Action	AssetActionUtility or ActorActionUtility; Beta
Reusable dockable UI with controls/progress	Editor Utility Widget	UMG-based; Beta
Action on one placed Actor, possibly shared with runtime	Call in Editor	Avoid editor-only nodes in runtime-capable classes
Interactive viewport manipulation	Scriptable Tool	Modal, accept/cancel lifecycle; Beta
Cross-tool pipeline or large scripted batch	Python	Editor-only; Experimental in 5.8
Deterministic editor extension/API	C++ editor module/plugin	Best for stable shared tooling and native tests
Headless repeatable batch	Commandlet or command-line Python	Prefer for CI; prove exit code and report output
Asset correctness	Data Validation	IsDataValid/UEditorValidatorBase
Code/system behavior	Automation Test	C++ framework, specs, low-level tests as appropriate
Gameplay/map behavior	Functional Test	Actor-based test in a level
AI invokes bounded editor functions	Unreal MCP	Experimental 5.8 server; schema-driven tools

Architecture

Split every nontrivial tool into:

UI / command / MCP adapter
  -> validated request
  -> discovery and dry-run plan
  -> mutation service
  -> save/source-control boundary
  -> validation and structured report

Keep domain logic out of widget graphs and MCP transport handlers. A shared C++/Blueprint library or Python module should make the same operation callable from UI, CI, or tests without duplicating behavior.

Escalation rule

Use the least powerful surface that fits. A one-selection rename does not need a global startup object; a CI validator does not need a dockable UI; an AI tool should expose one typed intent, not a general “execute arbitrary Python” endpoint.