diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotation.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotation.cs
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotationExtensions.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotationExtensions.cs
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotationKind.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotationKind.cs
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotationReference.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/AIAnnotationReference.cs
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/DataContent.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/DataContent.cs
index 5bbde1e1444..57f7fac1962 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/DataContent.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/DataContent.cs
@@ -183,6 +183,13 @@ public string Uri
     [JsonIgnore]
     public string MediaType { get; }
 
+    /// <summary>Gets or sets an optional name associated with the data.</summary>
+    /// <remarks>
+    /// A service might use this name as part of citations or to help infer the type of data
+    /// being represented based on a file extension.
+    /// </remarks>
+    public string? Name { get; set; }
+
     /// <summary>Gets the data represented by this instance.</summary>
     /// <remarks>
     /// If the instance was constructed from a <see cref="ReadOnlyMemory{Byte}"/>, this property returns that data.
diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.json b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.json
index b47765269af..4d190fccda8 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.json
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/Microsoft.Extensions.AI.Abstractions.json
@@ -1349,6 +1349,10 @@
           "Member": "System.ReadOnlyMemory<byte> Microsoft.Extensions.AI.DataContent.Data { get; }",
           "Stage": "Stable"
         },
+        {
+          "Member": "string? Microsoft.Extensions.AI.DataContent.Name { get; set; }",
+          "Stage": "Stable"
+        },
         {
           "Member": "string Microsoft.Extensions.AI.DataContent.MediaType { get; }",
           "Stage": "Stable"
diff --git a/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIChatClient.cs b/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIChatClient.cs
index 394fccad1b6..52dfc3dc8af 100644
--- a/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIChatClient.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIChatClient.cs
@@ -264,7 +264,7 @@ private static List<ChatMessageContentPart> ToOpenAIChatContent(IList<AIContent>
                 break;
 
             case DataContent dataContent when dataContent.MediaType.StartsWith("application/pdf", StringComparison.OrdinalIgnoreCase):
-                return ChatMessageContentPart.CreateFilePart(BinaryData.FromBytes(dataContent.Data), dataContent.MediaType, $"{Guid.NewGuid():N}.pdf");
+                return ChatMessageContentPart.CreateFilePart(BinaryData.FromBytes(dataContent.Data), dataContent.MediaType, dataContent.Name ?? $"{Guid.NewGuid():N}.pdf");
 
             case AIContent when content.RawRepresentation is ChatMessageContentPart rawContentPart:
                 return rawContentPart;
diff --git a/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIResponseChatClient.cs b/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIResponseChatClient.cs
index c4a1261844c..57ed46721b0 100644
--- a/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIResponseChatClient.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIResponseChatClient.cs
@@ -639,7 +639,7 @@ private static List<ResponseContentPart> ToOpenAIResponsesContent(IList<AIConten
                     break;
 
                 case DataContent dataContent when dataContent.MediaType.StartsWith("application/pdf", StringComparison.OrdinalIgnoreCase):
-                    parts.Add(ResponseContentPart.CreateInputFilePart(BinaryData.FromBytes(dataContent.Data), dataContent.MediaType, $"{Guid.NewGuid():N}.pdf"));
+                    parts.Add(ResponseContentPart.CreateInputFilePart(BinaryData.FromBytes(dataContent.Data), dataContent.MediaType, dataContent.Name ?? $"{Guid.NewGuid():N}.pdf"));
                     break;
 
                 case ErrorContent errorContent when errorContent.ErrorCode == nameof(ResponseContentPartKind.Refusal):
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIAnnotationReferenceTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIAnnotationReferenceTests.cs
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIAnnotationTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIAnnotationTests.cs
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIContentAnnotationTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/AIContentAnnotationTests.cs
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/DataContentTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/DataContentTests.cs
index 0f5b6b22d92..47bc6ccfd62 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/DataContentTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Contents/DataContentTests.cs
@@ -111,13 +111,20 @@ public void Serialize_MatchesExpectedJson()
     {
         Assert.Equal(
             """{"uri":"data:application/octet-stream;base64,AQIDBA=="}""",
-            JsonSerializer.Serialize(new DataContent(
-                uri: "data:application/octet-stream;base64,AQIDBA=="), TestJsonSerializerContext.Default.Options));
+            JsonSerializer.Serialize(
+                new DataContent(uri: "data:application/octet-stream;base64,AQIDBA=="),
+                TestJsonSerializerContext.Default.Options));
 
         Assert.Equal(
             """{"uri":"data:application/octet-stream;base64,AQIDBA=="}""",
-            JsonSerializer.Serialize(new DataContent(
-                new ReadOnlyMemory<byte>([0x01, 0x02, 0x03, 0x04]), "application/octet-stream"),
+            JsonSerializer.Serialize(
+                new DataContent(new ReadOnlyMemory<byte>([0x01, 0x02, 0x03, 0x04]), "application/octet-stream"),
+                TestJsonSerializerContext.Default.Options));
+
+        Assert.Equal(
+            """{"uri":"data:application/octet-stream;base64,AQIDBA==","name":"test.bin"}""",
+            JsonSerializer.Serialize(
+                new DataContent(new ReadOnlyMemory<byte>([0x01, 0x02, 0x03, 0x04]), "application/octet-stream") { Name = "test.bin" },
                 TestJsonSerializerContext.Default.Options));
     }
 
@@ -260,4 +267,13 @@ public void NonBase64Data_Normalized()
         Assert.Equal("aGVsbG8gd29ybGQ=", content.Base64Data.ToString());
         Assert.Equal("hello world", Encoding.ASCII.GetString(content.Data.ToArray()));
     }
+
+    [Fact]
+    public void FileName_Roundtrips()
+    {
+        DataContent content = new(new byte[] { 1, 2, 3 }, "application/octet-stream");
+        Assert.Null(content.Name);
+        content.Name = "test.bin";
+        Assert.Equal("test.bin", content.Name);
+    }
 }
diff --git a/test/Libraries/Microsoft.Extensions.AI.Integration.Tests/ChatClientIntegrationTests.cs b/test/Libraries/Microsoft.Extensions.AI.Integration.Tests/ChatClientIntegrationTests.cs
index ffa94f64531..c9f0e09abf3 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Integration.Tests/ChatClientIntegrationTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Integration.Tests/ChatClientIntegrationTests.cs
@@ -202,7 +202,7 @@ public virtual async Task MultiModal_DescribePdf()
                 new(ChatRole.User,
                 [
                     new TextContent("What text does this document contain?"),
-                    new DataContent(ImageDataUri.GetPdfDataUri(), "application/pdf"),
+                    new DataContent(ImageDataUri.GetPdfDataUri(), "application/pdf") { Name = "sample.pdf" },
                 ])
             ],
             new() { ModelId = GetModel_MultiModal_DescribeImage() });