diff --git a/src/toolbar/actionTypes.js b/src/toolbar/actionTypes.js
index 14f1c73..fc7c20f 100644
--- a/src/toolbar/actionTypes.js
+++ b/src/toolbar/actionTypes.js
@@ -1 +1,2 @@
+/** Dispatched when a toolbar button is clicked. Payload: { id: string } Action handled by toolbarButtonReducer. */
 export const CLICK_BUTTON = 'toolbar/CLICK_BUTTON';