diff --git a/sdk/src/main/java/com/oursky/authgear/AuthenticateOptions.kt b/sdk/src/main/java/com/oursky/authgear/AuthenticateOptions.kt
index 1c76eb5..b9c3869 100644
--- a/sdk/src/main/java/com/oursky/authgear/AuthenticateOptions.kt
+++ b/sdk/src/main/java/com/oursky/authgear/AuthenticateOptions.kt
@@ -15,7 +15,7 @@ data class AuthenticateOptions @JvmOverloads constructor(
      */
     var state: String? = null,
     /**
-     * Custom state.
+     * Use this parameter to provide parameters from the client application to Custom UI. The string in xState can be accessed by the Custom UI. Ignore this parameter if default AuthUI is used
      */
     var xState: String? = null,
     /**
diff --git a/sdk/src/main/java/com/oursky/authgear/PromoteOptions.kt b/sdk/src/main/java/com/oursky/authgear/PromoteOptions.kt
index 409aa1d..0c67bea 100644
--- a/sdk/src/main/java/com/oursky/authgear/PromoteOptions.kt
+++ b/sdk/src/main/java/com/oursky/authgear/PromoteOptions.kt
@@ -10,7 +10,7 @@ data class PromoteOptions @JvmOverloads constructor(
      */
     var state: String? = null,
     /**
-     * Custom state.
+     * Use this parameter to provide parameters from the client application to Custom UI. The string in xState can be accessed by the Custom UI. Ignore this parameter if default AuthUI is used
      */
     var xState: String? = null,
     /**
diff --git a/sdk/src/main/java/com/oursky/authgear/ReauthenticateOptions.kt b/sdk/src/main/java/com/oursky/authgear/ReauthenticateOptions.kt
index b39eb53..cc43751 100644
--- a/sdk/src/main/java/com/oursky/authgear/ReauthenticateOptions.kt
+++ b/sdk/src/main/java/com/oursky/authgear/ReauthenticateOptions.kt
@@ -15,7 +15,7 @@ data class ReauthenticateOptions @JvmOverloads constructor(
      */
     var state: String? = null,
     /**
-     * Custom state.
+     * Use this parameter to provide parameters from the client application to Custom UI. The string in xState can be accessed by the Custom UI. Ignore this parameter if default AuthUI is used
      */
     var xState: String? = null,
     /**