From b150511407c7262a6b81151abe2154e47e1c1c0f Mon Sep 17 00:00:00 2001
From: Jiaming Liang <jiamlia@microsoft.com>
Date: Tue, 21 Oct 2025 11:11:54 +0800
Subject: [PATCH] Respect custom ToolChoice and ParallelToolCallsEnabled
 options in OpenAIResponseAgent

---
 .../ResponseCreationOptionsFactory.cs         | 10 ++-
 .../ResponseCreationOptionsFactoryTests.cs    | 61 +++++++++++++++++++
 2 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/dotnet/src/Agents/OpenAI/Internal/ResponseCreationOptionsFactory.cs b/dotnet/src/Agents/OpenAI/Internal/ResponseCreationOptionsFactory.cs
index de288614ba9e..9dc9b8df6aab 100644
--- a/dotnet/src/Agents/OpenAI/Internal/ResponseCreationOptionsFactory.cs
+++ b/dotnet/src/Agents/OpenAI/Internal/ResponseCreationOptionsFactory.cs
@@ -60,8 +60,14 @@ internal static ResponseCreationOptions CreateOptions(
         if (responseTools is not null && responseTools.Any())
         {
             creationOptions.Tools.AddRange(responseTools);
-            creationOptions.ToolChoice = ResponseToolChoice.CreateAutoChoice();
-            creationOptions.ParallelToolCallsEnabled = true;
+            if (creationOptions.ToolChoice == null)
+            {
+                creationOptions.ToolChoice = ResponseToolChoice.CreateAutoChoice();
+            }
+            if (!creationOptions.ParallelToolCallsEnabled.HasValue)
+            {
+                creationOptions.ParallelToolCallsEnabled = true;
+            }
         }
 
         return creationOptions;
diff --git a/dotnet/src/Agents/UnitTests/OpenAI/Internal/ResponseCreationOptionsFactoryTests.cs b/dotnet/src/Agents/UnitTests/OpenAI/Internal/ResponseCreationOptionsFactoryTests.cs
index e92a4f2fb82a..a32393f48c3b 100644
--- a/dotnet/src/Agents/UnitTests/OpenAI/Internal/ResponseCreationOptionsFactoryTests.cs
+++ b/dotnet/src/Agents/UnitTests/OpenAI/Internal/ResponseCreationOptionsFactoryTests.cs
@@ -261,6 +261,60 @@ public void CreateOptionsWithNullAgentNameTest()
         Assert.Equal("UnnamedAgent", options.EndUserId); // Null name should fallback to "UnnamedAgent"
     }
 
+    /// <summary>
+    /// Verify response options creation with kernel plugin and default response options.
+    /// </summary>
+    [Fact]
+    public void CreateOptionsWithKernelPluginAndDefaultOptionsTest()
+    {
+        // Arrange
+        var mockAgent = CreateMockAgent("Test Agent", "You are a helpful assistant.", storeEnabled: false);
+        var mockThread = CreateMockAgentThread(null);
+        mockAgent.Kernel.Plugins.AddFromObject(new TestPlugin());
+
+        // Act
+        var options = ResponseCreationOptionsFactory.CreateOptions(mockAgent, mockThread.Object, null);
+
+        // Assert
+        Assert.NotNull(options);
+        Assert.Single(options.Tools);
+        Assert.NotNull(options.ToolChoice);
+        Assert.Equal(ResponseToolChoiceKind.Auto, options.ToolChoice.Kind);
+        Assert.True(options.ParallelToolCallsEnabled);
+    }
+
+    /// <summary>
+    /// Verify response options creation with kernel plugin and custom response options.
+    /// </summary>
+    [Fact]
+    public void CreateOptionsWithKernelPluginAndCustomOptionsTest()
+    {
+        // Arrange
+        var mockAgent = CreateMockAgent("Test Agent", "You are a helpful assistant.", storeEnabled: false);
+        var mockThread = CreateMockAgentThread(null);
+        mockAgent.Kernel.Plugins.AddFromObject(new TestPlugin());
+
+        // Custom invoke options should be respected
+        var invokeOptions = new OpenAIResponseAgentInvokeOptions
+        {
+            ResponseCreationOptions = new ResponseCreationOptions
+            {
+                ToolChoice = ResponseToolChoice.CreateNoneChoice(),
+                ParallelToolCallsEnabled = false
+            }
+        };
+
+        // Act
+        var options = ResponseCreationOptionsFactory.CreateOptions(mockAgent, mockThread.Object, invokeOptions);
+
+        // Assert
+        Assert.NotNull(options);
+        Assert.Single(options.Tools);
+        Assert.NotNull(options.ToolChoice);
+        Assert.Equal(ResponseToolChoiceKind.None, options.ToolChoice.Kind);
+        Assert.False(options.ParallelToolCallsEnabled);
+    }
+
     private static OpenAIResponseAgent CreateMockAgent(string? name, string? instructions, bool storeEnabled)
     {
         var mockClient = new Mock<OpenAIResponseClient>();
@@ -281,4 +335,11 @@ private static Mock<AgentThread> CreateMockAgentThread(string? threadId)
         mockThread.Setup(t => t.Id).Returns(threadId);
         return mockThread;
     }
+
+    private sealed class TestPlugin
+    {
+        [KernelFunction]
+        public void TestFunction()
+        { }
+    }
 }