Quick answer: Godot 4 C# [Export] property with [ExportToolButton] not appearing in editor? Tool attributes require [Tool] on the script - add it at class level.
Editor utility script has [ExportToolButton("Regenerate")]. Button doesn't appear in the inspector.
Add [Tool] to class
[Tool]
public partial class Generator : Node { ... }Without [Tool], the script doesn't run in editor and tool buttons don't display.
Verify with EngineRuntimeContext
In a tool method, check Engine.IsEditorHint(). True = running in editor. The check confirms the [Tool] attribute is active.
Or use [EditorOnly]
Specific attribute for editor-only methods. Slightly different semantics; useful for one-off utilities.
“Editor-time code requires [Tool]. Without it, editor doesn't load the script.”
If your tool button doesn't show, [Tool] is the first thing to check. Document the requirement at the top of every tool script.