diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIContent.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIContent.cs
index af8b19c8d84..1bfc61e0a38 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIContent.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIContent.cs
@@ -32,6 +32,8 @@ namespace Microsoft.Extensions.AI;
 // [JsonDerivedType(typeof(McpServerToolApprovalResponseContent), typeDiscriminator: "mcpServerToolApprovalResponse")]
 // [JsonDerivedType(typeof(CodeInterpreterToolCallContent), typeDiscriminator: "codeInterpreterToolCall")]
 // [JsonDerivedType(typeof(CodeInterpreterToolResultContent), typeDiscriminator: "codeInterpreterToolResult")]
+// [JsonDerivedType(typeof(AdditionalDetailsRequestContent), typeDiscriminator: "additionalDetailsRequestContent")]
+// [JsonDerivedType(typeof(AdditionalDetailsResponseContent), typeDiscriminator: "additionalDetailsResponseContent")]
 
 public class AIContent
 {
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AdditionalDetailsRequestContent.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AdditionalDetailsRequestContent.cs
new file mode 100644
index 00000000000..704d4cba0c2
--- /dev/null
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AdditionalDetailsRequestContent.cs
@@ -0,0 +1,43 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Extensions.AI;
+
+/// <summary>
+/// Represents a request for additional details from the user.
+/// </summary>
+[Experimental("MEAI001")]
+public sealed class AdditionalDetailsRequestContent : UserInputRequestContent
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AdditionalDetailsRequestContent"/> class.
+    /// </summary>
+    /// <param name="id">The ID that uniquely identifies the additional details request/response pair.</param>
+    /// <param name="request">The additional details request.</param>
+    /// <exception cref="ArgumentNullException"><paramref name="id"/> is <see langword="null"/>.</exception>
+    /// <exception cref="ArgumentException"><paramref name="id"/> is empty or composed entirely of whitespace.</exception>
+    /// <exception cref="ArgumentNullException"><paramref name="request"/> is <see langword="null"/>.</exception>
+    public AdditionalDetailsRequestContent(string id, AIContent request)
+        : base(id)
+    {
+        Request = Throw.IfNull(request);
+    }
+
+    /// <summary>
+    /// Gets the additional details request.
+    /// </summary>
+    public AIContent Request { get; }
+
+    /// <summary>
+    /// Creates a <see cref="AdditionalDetailsResponseContent"/> to provide the requested additional details.
+    /// </summary>
+    /// <param name="response">The <see cref="AIContent"/> containing the requested additional details.</param>
+    /// <returns>The <see cref="AdditionalDetailsResponseContent"/> representing the response.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="response"/> is <see langword="null"/>.</exception>
+    public AdditionalDetailsResponseContent CreateResponse(AIContent response) => new(Id, response);
+}
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AdditionalDetailsResponseContent.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AdditionalDetailsResponseContent.cs
new file mode 100644
index 00000000000..a20980c2aeb
--- /dev/null
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AdditionalDetailsResponseContent.cs
@@ -0,0 +1,35 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Extensions.AI;
+
+/// <summary>
+/// Represents a response for additional details request from the user.
+/// </summary>
+[Experimental("MEAI001")]
+public sealed class AdditionalDetailsResponseContent : UserInputResponseContent
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AdditionalDetailsResponseContent"/> class.
+    /// </summary>
+    /// <param name="id">The ID that uniquely identifies the additional details request/response pair.</param>
+    /// <param name="response">The additional details response.</param>
+    /// <exception cref="ArgumentNullException"><paramref name="id"/> is <see langword="null"/>.</exception>
+    /// <exception cref="ArgumentException"><paramref name="id"/> is empty or composed entirely of whitespace.</exception>
+    /// <exception cref="ArgumentNullException"><paramref name="response"/> is <see langword="null"/>.</exception>
+    public AdditionalDetailsResponseContent(string id, AIContent response)
+        : base(id)
+    {
+        Response = Throw.IfNull(response);
+    }
+
+    /// <summary>
+    /// Gets the additional details response.
+    /// </summary>
+    public AIContent Response { get; }
+}
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputRequestContent.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputRequestContent.cs
index b2a2e0e6e95..267bfe3c4dc 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputRequestContent.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputRequestContent.cs
@@ -15,6 +15,7 @@ namespace Microsoft.Extensions.AI;
 [JsonPolymorphic(TypeDiscriminatorPropertyName = "$type")]
 [JsonDerivedType(typeof(FunctionApprovalRequestContent), "functionApprovalRequest")]
 [JsonDerivedType(typeof(McpServerToolApprovalRequestContent), "mcpServerToolApprovalRequest")]
+[JsonDerivedType(typeof(AdditionalDetailsRequestContent), "additionalDetailsRequestContent")]
 public class UserInputRequestContent : AIContent
 {
     /// <summary>
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputResponseContent.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputResponseContent.cs
index 6902f047282..980f84dcb61 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputResponseContent.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/UserInputResponseContent.cs
@@ -15,6 +15,7 @@ namespace Microsoft.Extensions.AI;
 [JsonPolymorphic(TypeDiscriminatorPropertyName = "$type")]
 [JsonDerivedType(typeof(FunctionApprovalResponseContent), "functionApprovalResponse")]
 [JsonDerivedType(typeof(McpServerToolApprovalResponseContent), "mcpServerToolApprovalResponse")]
+[JsonDerivedType(typeof(AdditionalDetailsResponseContent), "additionalDetailsResponseContent")]
 public class UserInputResponseContent : AIContent
 {
     /// <summary>
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Defaults.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Defaults.cs
index d01294836bc..8b1c1fb1996 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Defaults.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Defaults.cs
@@ -59,6 +59,8 @@ private static JsonSerializerOptions CreateDefaultOptions()
         AddAIContentType(options, typeof(McpServerToolApprovalResponseContent), typeDiscriminatorId: "mcpServerToolApprovalResponse", checkBuiltIn: false);
         AddAIContentType(options, typeof(CodeInterpreterToolCallContent), typeDiscriminatorId: "codeInterpreterToolCall", checkBuiltIn: false);
         AddAIContentType(options, typeof(CodeInterpreterToolResultContent), typeDiscriminatorId: "codeInterpreterToolResult", checkBuiltIn: false);
+        AddAIContentType(options, typeof(AdditionalDetailsRequestContent), typeDiscriminatorId: "additionalDetailsRequestContent", checkBuiltIn: false);
+        AddAIContentType(options, typeof(AdditionalDetailsResponseContent), typeDiscriminatorId: "additionalDetailsResponseContent", checkBuiltIn: false);
 
         if (JsonSerializer.IsReflectionEnabledByDefault)
         {
@@ -133,6 +135,8 @@ private static JsonSerializerOptions CreateDefaultOptions()
     [JsonSerializable(typeof(McpServerToolApprovalResponseContent))]
     [JsonSerializable(typeof(CodeInterpreterToolCallContent))]
     [JsonSerializable(typeof(CodeInterpreterToolResultContent))]
+    [JsonSerializable(typeof(AdditionalDetailsRequestContent))]
+    [JsonSerializable(typeof(AdditionalDetailsResponseContent))]
     [JsonSerializable(typeof(ResponseContinuationToken))]
 
     // IEmbeddingGenerator
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIContentTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIContentTests.cs
index e5734ccd7cf..152eea7dcf1 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIContentTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIContentTests.cs
@@ -75,7 +75,9 @@ public void Serialization_DerivedTypes_Roundtrips()
             new McpServerToolCallContent("call123", "myTool", "myServer"),
             new McpServerToolResultContent("call123"),
             new McpServerToolApprovalRequestContent("request123", new McpServerToolCallContent("call123", "myTool", "myServer")),
-            new McpServerToolApprovalResponseContent("request123", approved: true)
+            new McpServerToolApprovalResponseContent("request123", approved: true),
+            new AdditionalDetailsRequestContent("request123", new TextContent("Please provide the image you mentioned but did not provide.")),
+            new AdditionalDetailsResponseContent("response123", new DataContent(new byte[]{ 1, 2, 3 }, "image/jpeg"))
         ]);
 
         var serialized = JsonSerializer.Serialize(message, AIJsonUtilities.DefaultOptions);
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AdditionalDetailsRequestContentTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AdditionalDetailsRequestContentTests.cs
new file mode 100644
index 00000000000..247137dd288
--- /dev/null
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AdditionalDetailsRequestContentTests.cs
@@ -0,0 +1,66 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Text.Json;
+using Xunit;
+
+namespace Microsoft.Extensions.AI.Contents;
+
+public class AdditionalDetailsRequestContentTests
+{
+    [Fact]
+    public void Constructor_InvalidArguments_Throws()
+    {
+        Assert.Throws<ArgumentNullException>("id", () => new AdditionalDetailsRequestContent(null!, new TextContent("request")));
+        Assert.Throws<ArgumentException>("id", () => new AdditionalDetailsRequestContent("", new TextContent("request")));
+        Assert.Throws<ArgumentException>("id", () => new AdditionalDetailsRequestContent("\r\t\n ", new TextContent("request")));
+
+        Assert.Throws<ArgumentNullException>("request", () => new AdditionalDetailsRequestContent("id", null!));
+    }
+
+    [Fact]
+    public void Constructor_Roundtrips()
+    {
+        string id = "abc";
+        TextContent request = new("What is your name?");
+        AdditionalDetailsRequestContent content = new(id, request);
+
+        Assert.Same(id, content.Id);
+        Assert.Same(request, content.Request);
+    }
+
+    [Fact]
+    public void CreateResponse_ReturnsExpectedResponse()
+    {
+        string id = "req-1";
+        string request = "What is your name?";
+        TextContent response = new TextContent("My name is John");
+
+        AdditionalDetailsRequestContent content = new(id, new TextContent(request));
+
+        var textResponse = content.CreateResponse(response);
+
+        Assert.NotNull(textResponse);
+        Assert.Same(id, textResponse.Id);
+        Assert.Same(response, textResponse.Response);
+        Assert.Throws<ArgumentNullException>("response", () => content.CreateResponse(null!));
+    }
+
+    [Fact]
+    public void Serialization_Roundtrips()
+    {
+        var content = new AdditionalDetailsRequestContent("request123", new TextContent("What is your name?"));
+
+        var json = JsonSerializer.Serialize(content, AIJsonUtilities.DefaultOptions);
+        var deserializedContent = JsonSerializer.Deserialize<AdditionalDetailsRequestContent>(json, AIJsonUtilities.DefaultOptions);
+
+        Assert.NotNull(deserializedContent);
+        Assert.Equal(content.Id, deserializedContent.Id);
+
+        TextContent originalRequest = Assert.IsType<TextContent>(content.Request);
+        TextContent deserializedRequest = Assert.IsType<TextContent>(deserializedContent.Request);
+
+        Assert.Equal(originalRequest.Text, deserializedRequest.Text);
+    }
+}
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AdditionalDetailsResponseContentTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AdditionalDetailsResponseContentTests.cs
new file mode 100644
index 00000000000..34f847a3b51
--- /dev/null
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AdditionalDetailsResponseContentTests.cs
@@ -0,0 +1,49 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Text.Json;
+using Xunit;
+
+namespace Microsoft.Extensions.AI.Contents;
+
+public class AdditionalDetailsResponseContentTests
+{
+    [Fact]
+    public void Constructor_InvalidArguments_Throws()
+    {
+        Assert.Throws<ArgumentNullException>("id", () => new AdditionalDetailsResponseContent(null!, new TextContent("response")));
+        Assert.Throws<ArgumentException>("id", () => new AdditionalDetailsResponseContent("", new TextContent("response")));
+        Assert.Throws<ArgumentException>("id", () => new AdditionalDetailsResponseContent("\r\t\n ", new TextContent("response")));
+
+        Assert.Throws<ArgumentNullException>("response", () => new AdditionalDetailsResponseContent("id", null!));
+    }
+
+    [Fact]
+    public void Constructor_Roundtrips()
+    {
+        string id = "test-id";
+        TextContent response = new("test-response");
+        AdditionalDetailsResponseContent content = new(id, response);
+
+        Assert.Same(id, content.Id);
+        Assert.Same(response, content.Response);
+    }
+
+    [Fact]
+    public void Serialization_Roundtrips()
+    {
+        var content = new AdditionalDetailsResponseContent("response123", new TextContent("This is my answer"));
+
+        var json = JsonSerializer.Serialize(content, AIJsonUtilities.DefaultOptions);
+        var deserializedContent = JsonSerializer.Deserialize<AdditionalDetailsResponseContent>(json, AIJsonUtilities.DefaultOptions);
+
+        Assert.NotNull(deserializedContent);
+        Assert.Equal(content.Id, deserializedContent.Id);
+
+        TextContent originalResponse = Assert.IsType<TextContent>(content.Response);
+        TextContent deserializedResponse = Assert.IsType<TextContent>(deserializedContent.Response);
+
+        Assert.Equal(originalResponse.Text, deserializedResponse.Text);
+    }
+}
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputRequestContentTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputRequestContentTests.cs
index fc4dac9cabb..8d0b5e62a1b 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputRequestContentTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputRequestContentTests.cs
@@ -43,6 +43,7 @@ public void Serialization_DerivedTypes_Roundtrips()
         [
             new FunctionApprovalRequestContent("request123", new FunctionCallContent("call123", "functionName", new Dictionary<string, object?> { { "param1", 123 } })),
             new McpServerToolApprovalRequestContent("request123", new McpServerToolCallContent("call123", "myTool", "myServer")),
+            new AdditionalDetailsRequestContent("request123", new TextContent("I need more details. Where would you like to fly from and to?")),
         ];
 
         var serializedContents = JsonSerializer.Serialize(contents, TestJsonSerializerContext.Default.UserInputRequestContentArray);
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputResponseContentTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputResponseContentTests.cs
index 2442e57272d..3916546e437 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputResponseContentTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/UserInputResponseContentTests.cs
@@ -41,6 +41,7 @@ public void Serialization_DerivedTypes_Roundtrips()
         [
             new FunctionApprovalResponseContent("request123", true, new FunctionCallContent("call123", "functionName")),
             new McpServerToolApprovalResponseContent("request123", true),
+            new AdditionalDetailsResponseContent("response123", new TextContent("I would like to fly from New York to San Francisco."))
         ];
 
         var serializedContents = JsonSerializer.Serialize(contents, TestJsonSerializerContext.Default.UserInputResponseContentArray);