diff --git a/Anthropic.SDK/Constants/AnthropicModels.cs b/Anthropic.SDK/Constants/AnthropicModels.cs
index 5ef4b62..6111bb9 100644
--- a/Anthropic.SDK/Constants/AnthropicModels.cs
+++ b/Anthropic.SDK/Constants/AnthropicModels.cs
@@ -50,6 +50,11 @@ public static class AnthropicModels
         /// </summary>
         public const string Claude35Haiku = "claude-3-5-haiku-20241022";
 
+        /// <summary>
+        /// Claude 4.5 Haiku
+        /// </summary>
+        public const string Claude45Haiku = "claude-haiku-4-5-20251001";
+
         /// <summary>
         /// Claude 3 Haiku
         /// </summary>
diff --git a/Anthropic.SDK/Constants/VertexAIModels.cs b/Anthropic.SDK/Constants/VertexAIModels.cs
index 663655f..b77dccb 100644
--- a/Anthropic.SDK/Constants/VertexAIModels.cs
+++ b/Anthropic.SDK/Constants/VertexAIModels.cs
@@ -31,22 +31,27 @@ public static class VertexAIModels
         public const string Claude37Sonnet = "claude-3-7-sonnet@20250219";
 
         /// <summary>
-        /// Claude 4 Sonnet
+        /// Claude 4 Sonnet on Vertex AI
         /// </summary>
         public const string Claude4Sonnet = "claude-sonnet-4@20250514";
 
         /// <summary>
-        /// Claude 4.5 Sonnet
+        /// Claude 4.5 Sonnet on Vertex AI
         /// </summary>
-        public const string Claude45Sonnet = "claude-sonnet-4@20250514";
+        public const string Claude45Sonnet = "claude-sonnet-4-5@20250929";
 
         /// <summary>
-        /// Claude 4 Opus
+        /// Claude 4.5 Haiku on Vertex AI
         /// </summary>
-        public const string Claude4Opus = "claude-sonnet-4-5@20250929";
+        public const string Claude45Haiku = "claude-haiku-4-5@20251001";
 
         /// <summary>
-        /// Claude 4.1 Opus
+        /// Claude 4 Opus on Vertex AI
+        /// </summary>
+        public const string Claude4Opus = "claude-opus-4@20250514";
+
+        /// <summary>
+        /// Claude 4.1 Opus on Vertex AI
         /// </summary>
         public const string Claude41Opus = "claude-opus-4-1@20250805"; 
     }