diff --git a/core/java/android/os/Vibrator.java b/core/java/android/os/Vibrator.java
index 465d90d366984..4137ca18b068d 100644
--- a/core/java/android/os/Vibrator.java
+++ b/core/java/android/os/Vibrator.java
@@ -527,7 +527,8 @@ public abstract class Vibrator {
     }
 
     /**
-     * Query whether the vibrator supports all the given effects.
+     * Query whether the vibrator supports all the given effects. If no argument is provided this
+     * method will always return {@link #VIBRATION_EFFECT_SUPPORT_YES}.
      *
      * <p>If an effect is not supported, the system may still automatically fall back to a simpler
      * vibration instead, which is not optimised for the specific device, however vibration isn't
@@ -549,7 +550,8 @@ public abstract class Vibrator {
      * <p>Use {@link #areEffectsSupported(int...)} to get individual results for each effect.
      *
      * @param effectIds Which effects to query for.
-     * @return Whether all the effects are natively supported by the device.
+     * @return Whether all specified effects are natively supported by the device. Empty query
+     * defaults to {@link #VIBRATION_EFFECT_SUPPORT_YES}.
      */
     @VibrationEffectSupport
     public final int areAllEffectsSupported(
@@ -598,7 +600,8 @@ public abstract class Vibrator {
     }
 
     /**
-     * Query whether the vibrator supports all of the given primitives.
+     * Query whether the vibrator supports all of the given primitives.  If no argument is provided
+     * this method will always return {@code true}.
      *
      * <p>If a primitive is not supported by the device, then <em>no vibration</em> will occur if
      * it is played.
@@ -606,7 +609,7 @@ public abstract class Vibrator {
      * <p>Use {@link #arePrimitivesSupported(int...)} to get individual results for each primitive.
      *
      * @param primitiveIds Which primitives to query for.
-     * @return Whether all specified primitives are supported.
+     * @return Whether all specified primitives are supported. Empty query defaults to {@code true}.
      */
     public final boolean areAllPrimitivesSupported(
             @NonNull @VibrationEffect.Composition.PrimitiveType int... primitiveIds) {