diff --git a/src/AnthropicClient/Models/BaseMessageRequest.cs b/src/AnthropicClient/Models/BaseMessageRequest.cs
index 04ac289..03a4809 100644
--- a/src/AnthropicClient/Models/BaseMessageRequest.cs
+++ b/src/AnthropicClient/Models/BaseMessageRequest.cs
@@ -126,7 +126,6 @@ public abstract class BaseMessageRequest
   /// <param name="stream">A value indicating whether the message should be streamed.</param>
   /// <param name="stopSequences">The prompt stop sequences.</param>
   /// <param name="systemMessages">The system messages to use for the request.</param>
-  /// <exception cref="ArgumentException">Thrown when the model ID is invalid.</exception>
   /// <exception cref="ArgumentNullException">Thrown when the model or messages is null.</exception>
   /// <exception cref="ArgumentException">Thrown when the messages contain no messages.</exception>
   /// <exception cref="ArgumentException">Thrown when the max tokens is less than one.</exception>
@@ -151,11 +150,6 @@ public abstract class BaseMessageRequest
     ArgumentValidator.ThrowIfNull(model, nameof(model));
     ArgumentValidator.ThrowIfNull(messages, nameof(messages));
 
-    if (AnthropicModels.IsValidModel(model) is false)
-    {
-      throw new ArgumentException($"Invalid model ID: {model}");
-    }
-
     if (messages.Count < 1)
     {
       throw new ArgumentException("Messages must contain at least one message");
diff --git a/src/AnthropicClient/Models/MessageRequest.cs b/src/AnthropicClient/Models/MessageRequest.cs
index f091dbf..d3f8771 100644
--- a/src/AnthropicClient/Models/MessageRequest.cs
+++ b/src/AnthropicClient/Models/MessageRequest.cs
@@ -25,7 +25,6 @@ public class MessageRequest : BaseMessageRequest
   /// <param name="tools">The tools to use for the request.</param>
   /// <param name="stopSequences">The prompt stop sequences.</param>
   /// <param name="systemMessages">The system messages to include with the request.</param>
-  /// <exception cref="ArgumentException">Thrown when the model ID is invalid.</exception>
   /// <exception cref="ArgumentNullException">Thrown when the model or messages is null.</exception>
   /// <exception cref="ArgumentException">Thrown when the messages contain no messages.</exception>
   /// <exception cref="ArgumentException">Thrown when the max tokens is less than one.</exception>
diff --git a/src/AnthropicClient/Models/StreamMessageRequest.cs b/src/AnthropicClient/Models/StreamMessageRequest.cs
index 402075e..f07c952 100644
--- a/src/AnthropicClient/Models/StreamMessageRequest.cs
+++ b/src/AnthropicClient/Models/StreamMessageRequest.cs
@@ -25,7 +25,6 @@ public class StreamMessageRequest : BaseMessageRequest
   /// <param name="tools">The tools to use for the request.</param>
   /// <param name="stopSequences">The prompt stop sequences.</param>
   /// <param name="systemMessages">The system messages to include with the request.</param>
-  /// <exception cref="ArgumentException">Thrown when the model ID is invalid.</exception>
   /// <exception cref="ArgumentNullException">Thrown when the model or messages is null.</exception>
   /// <exception cref="ArgumentException">Thrown when the messages contain no messages.</exception>
   /// <exception cref="ArgumentException">Thrown when the max tokens is less than one.</exception>
diff --git a/tests/AnthropicClient.Tests/Unit/Models/MessageRequestTests.cs b/tests/AnthropicClient.Tests/Unit/Models/MessageRequestTests.cs
index 2efd402..2e7e87c 100644
--- a/tests/AnthropicClient.Tests/Unit/Models/MessageRequestTests.cs
+++ b/tests/AnthropicClient.Tests/Unit/Models/MessageRequestTests.cs
@@ -232,14 +232,14 @@ public class MessageRequestTests : SerializationTest
   }
 
   [Fact]
-  public void Constructor_WhenCalledAndModelIsInvalid_ItShouldThrowArgumentException()
+  public void Constructor_WhenCalledAndModelIsInvalid_ItShouldNotThrowException()
   {
     var action = () => new MessageRequest(
       model: "invalid-model",
       messages: [new()]
     );
 
-    action.Should().Throw<ArgumentException>();
+    action.Should().NotThrow();
   }
 
   [Fact]
diff --git a/tests/AnthropicClient.Tests/Unit/Models/StreamMessageRequestTests.cs b/tests/AnthropicClient.Tests/Unit/Models/StreamMessageRequestTests.cs
index 67ebd1e..e09982f 100644
--- a/tests/AnthropicClient.Tests/Unit/Models/StreamMessageRequestTests.cs
+++ b/tests/AnthropicClient.Tests/Unit/Models/StreamMessageRequestTests.cs
@@ -85,14 +85,14 @@ public class StreamMessageRequestTests : SerializationTest
   }
 
   [Fact]
-  public void Constructor_WhenCalledAndModelIsInvalid_ItShouldThrowArgumentException()
+  public void Constructor_WhenCalledAndModelIsInvalid_ItShouldNotThrowException()
   {
     var action = () => new StreamMessageRequest(
       model: "invalid-model",
       messages: [new()]
     );
 
-    action.Should().Throw<ArgumentException>();
+    action.Should().NotThrow();
   }
 
   [Fact]