diff --git a/api/kotlin-sdk.api b/api/kotlin-sdk.api
index 411bb3d..cd74e0c 100644
--- a/api/kotlin-sdk.api
+++ b/api/kotlin-sdk.api
@@ -1485,8 +1485,9 @@ public final class io/modelcontextprotocol/kotlin/sdk/PingRequest$Companion {
 
 public class io/modelcontextprotocol/kotlin/sdk/Progress : io/modelcontextprotocol/kotlin/sdk/ProgressBase {
 	public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/Progress$Companion;
-	public synthetic fun <init> (IILjava/lang/Double;Lkotlinx/serialization/internal/SerializationConstructorMarker;)V
-	public fun <init> (ILjava/lang/Double;)V
+	public synthetic fun <init> (IILjava/lang/Double;Ljava/lang/String;Lkotlinx/serialization/internal/SerializationConstructorMarker;)V
+	public fun <init> (ILjava/lang/Double;Ljava/lang/String;)V
+	public fun getMessage ()Ljava/lang/String;
 	public fun getProgress ()I
 	public fun getTotal ()Ljava/lang/Double;
 	public static final synthetic fun write$Self (Lio/modelcontextprotocol/kotlin/sdk/Progress;Lkotlinx/serialization/encoding/CompositeEncoder;Lkotlinx/serialization/descriptors/SerialDescriptor;)V
@@ -1509,6 +1510,7 @@ public final class io/modelcontextprotocol/kotlin/sdk/Progress$Companion {
 
 public abstract interface class io/modelcontextprotocol/kotlin/sdk/ProgressBase {
 	public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/ProgressBase$Companion;
+	public abstract fun getMessage ()Ljava/lang/String;
 	public abstract fun getProgress ()I
 	public abstract fun getTotal ()Ljava/lang/Double;
 }
@@ -1519,15 +1521,17 @@ public final class io/modelcontextprotocol/kotlin/sdk/ProgressBase$Companion {
 
 public final class io/modelcontextprotocol/kotlin/sdk/ProgressNotification : io/modelcontextprotocol/kotlin/sdk/ClientNotification, io/modelcontextprotocol/kotlin/sdk/ProgressBase, io/modelcontextprotocol/kotlin/sdk/ServerNotification {
 	public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/ProgressNotification$Companion;
-	public fun <init> (ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;)V
-	public synthetic fun <init> (ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public fun <init> (ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;Ljava/lang/String;)V
+	public synthetic fun <init> (ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun component1 ()I
 	public final fun component2 ()Lio/modelcontextprotocol/kotlin/sdk/RequestId;
 	public final fun component3 ()Lkotlinx/serialization/json/JsonObject;
 	public final fun component4 ()Ljava/lang/Double;
-	public final fun copy (ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;)Lio/modelcontextprotocol/kotlin/sdk/ProgressNotification;
-	public static synthetic fun copy$default (Lio/modelcontextprotocol/kotlin/sdk/ProgressNotification;ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;ILjava/lang/Object;)Lio/modelcontextprotocol/kotlin/sdk/ProgressNotification;
+	public final fun component5 ()Ljava/lang/String;
+	public final fun copy (ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;Ljava/lang/String;)Lio/modelcontextprotocol/kotlin/sdk/ProgressNotification;
+	public static synthetic fun copy$default (Lio/modelcontextprotocol/kotlin/sdk/ProgressNotification;ILio/modelcontextprotocol/kotlin/sdk/RequestId;Lkotlinx/serialization/json/JsonObject;Ljava/lang/Double;Ljava/lang/String;ILjava/lang/Object;)Lio/modelcontextprotocol/kotlin/sdk/ProgressNotification;
 	public fun equals (Ljava/lang/Object;)Z
+	public fun getMessage ()Ljava/lang/String;
 	public fun getMethod ()Lio/modelcontextprotocol/kotlin/sdk/Method;
 	public fun getProgress ()I
 	public final fun getProgressToken ()Lio/modelcontextprotocol/kotlin/sdk/RequestId;
diff --git a/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/Protocol.kt b/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/Protocol.kt
index d9808ff..7553bf1 100644
--- a/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/Protocol.kt
+++ b/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/Protocol.kt
@@ -260,6 +260,7 @@ public abstract class Protocol(
         LOGGER.trace { "Received progress notification: token=${notification.progressToken}, progress=${notification.progress}/${notification.total}" }
         val progress = notification.progress
         val total = notification.total
+        val message = notification.message
         val progressToken = notification.progressToken
 
         val handler = progressHandlers[progressToken]
@@ -272,7 +273,7 @@ public abstract class Protocol(
             return
         }
 
-        handler.invoke(Progress(progress, total))
+        handler.invoke(Progress(progress, total, message))
     }
 
     private fun onResponse(response: JSONRPCResponse?, error: JSONRPCError?) {
diff --git a/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt b/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt
index c5e5456..c69d2d2 100644
--- a/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt
+++ b/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt
@@ -512,6 +512,11 @@ public sealed interface ProgressBase {
      * Total number of items to a process (or total progress required), if known.
      */
     public val total: Double?
+
+    /**
+     * An optional message describing the current progress.
+     */
+    public val message: String?
 }
 
 /* Progress notifications */
@@ -532,6 +537,11 @@ public open class Progress(
      * Total number of items to a process (or total progress required), if known.
      */
     override val total: Double?,
+
+    /**
+     * An optional message describing the current progress.
+     */
+    override val message: String?,
 ) : ProgressBase
 
 /**
@@ -548,6 +558,7 @@ public data class ProgressNotification(
     public val progressToken: ProgressToken,
     @Suppress("PropertyName") val _meta: JsonObject = EmptyJsonObject,
     override val total: Double?,
+    override val message: String?,
 ) : ClientNotification, ServerNotification, ProgressBase {
     override val method: Method = Method.Defined.NotificationsProgress
 }