diff --git a/src/npe2/_command_registry.py b/src/npe2/_command_registry.py
index 82a0c89e..5694bf23 100644
--- a/src/npe2/_command_registry.py
+++ b/src/npe2/_command_registry.py
@@ -39,6 +39,13 @@ def resolve(self) -> Callable:
 
 
 class CommandRegistry:
+    """Registry of commands, updated on `PluginManager.activate`.
+
+    `PluginManager.activate` is only run on `CommandRegistry.get` (when we resolve the
+    callable object for a command). This means that commands from enabled plugins are
+    not added to `CommandRegistry` until a command from that plugin is executed.
+    """
+
     command_registered = Signal(str)
     command_unregistered = Signal(str)