diff --git a/effectful-core/src/Effectful/Internal/Monad.hs b/effectful-core/src/Effectful/Internal/Monad.hs
index 3b7f6ae..19ba211 100644
--- a/effectful-core/src/Effectful/Internal/Monad.hs
+++ b/effectful-core/src/Effectful/Internal/Monad.hs
@@ -287,10 +287,15 @@ instance MonadFix (Eff es) where
 ----------------------------------------
 -- NonDet
 
--- | Provide the ability to use the 'Alternative' and 'MonadPlus' instance for
--- 'Eff'.
---
--- @since 2.2.0.0
+{-| Provide the ability to use the 'Alternative' and 'MonadPlus' instance for
+'Eff'.
+
+'NonDet' does not backtrack. Formally, it obeys the "left-catch" law for 'MonadPlus', 
+rather than the "left-distribution" law. This means that it behaves more like 'Maybe'
+than '[]'.
+
+@since 2.2.0.0
+-}
 data NonDet :: Effect where
   Empty   :: NonDet m a
   (:<|>:) :: m a -> m a -> NonDet m a