diff --git a/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryChatClient.cs b/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryChatClient.cs
index 326503bc04d..0803b35d464 100644
--- a/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryChatClient.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryChatClient.cs
@@ -22,7 +22,7 @@ namespace Microsoft.Extensions.AI;
 
 /// <summary>Represents a delegating chat client that implements the OpenTelemetry Semantic Conventions for Generative AI systems.</summary>
 /// <remarks>
-/// This class provides an implementation of the Semantic Conventions for Generative AI systems v1.41, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
+/// This class provides an implementation of the GenAI Semantic Conventions latest, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
 /// The specification is still experimental and subject to change; as such, the telemetry output by this client is also subject to change.
 /// </remarks>
 public sealed partial class OpenTelemetryChatClient : DelegatingChatClient
@@ -353,6 +353,23 @@ public override async IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseA
                         _ = activity.AddTag(OpenTelemetryConsts.GenAI.Request.TopP, top_p);
                     }
 
+                    if (options.Reasoning?.Effort is ReasoningEffort effort)
+                    {
+                        string? reasoningLevel = effort switch
+                        {
+                            ReasoningEffort.Low => "low",
+                            ReasoningEffort.Medium => "medium",
+                            ReasoningEffort.High => "high",
+                            ReasoningEffort.ExtraHigh => "extra_high",
+                            _ => null,
+                        };
+
+                        if (reasoningLevel is not null)
+                        {
+                            _ = activity.AddTag(OpenTelemetryConsts.GenAI.Request.ReasoningLevel, reasoningLevel);
+                        }
+                    }
+
                     if (options.ResponseFormat is not null)
                     {
                         switch (options.ResponseFormat)
diff --git a/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryImageGenerator.cs b/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryImageGenerator.cs
index a20b512c7b0..115ca26c74d 100644
--- a/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryImageGenerator.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryImageGenerator.cs
@@ -20,7 +20,7 @@ namespace Microsoft.Extensions.AI;
 
 /// <summary>Represents a delegating image generator that implements the OpenTelemetry Semantic Conventions for Generative AI systems.</summary>
 /// <remarks>
-/// This class provides an implementation of the Semantic Conventions for Generative AI systems v1.41, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
+/// This class provides an implementation of the GenAI Semantic Conventions latest, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
 /// The specification is still experimental and subject to change; as such, the telemetry output by this client is also subject to change.
 /// </remarks>
 [Experimental(DiagnosticIds.Experiments.AIImageGeneration, UrlFormat = DiagnosticIds.UrlFormat)]
diff --git a/src/Libraries/Microsoft.Extensions.AI/Common/OtelMessageSerializer.cs b/src/Libraries/Microsoft.Extensions.AI/Common/OtelMessageSerializer.cs
index c5916379508..1c62d838dac 100644
--- a/src/Libraries/Microsoft.Extensions.AI/Common/OtelMessageSerializer.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/Common/OtelMessageSerializer.cs
@@ -264,10 +264,12 @@ internal static string SerializeChatMessages(
             if (pos >= 0)
             {
                 ReadOnlySpan<char> topLevel = mediaType.AsSpan(0, pos);
+                ReadOnlySpan<char> subtype = mediaType.AsSpan(pos + 1);
                 return
                     topLevel.Equals("image", StringComparison.OrdinalIgnoreCase) ? "image" :
                     topLevel.Equals("audio", StringComparison.OrdinalIgnoreCase) ? "audio" :
                     topLevel.Equals("video", StringComparison.OrdinalIgnoreCase) ? "video" :
+                    IsDocumentMediaType(topLevel, subtype) ? "document" :
                     null;
             }
         }
@@ -275,6 +277,19 @@ internal static string SerializeChatMessages(
         return null;
     }
 
+    /// <summary>Returns <see langword="true"/> when the media type represents a document (PDF, Office, ODF, RTF, …).</summary>
+    private static bool IsDocumentMediaType(ReadOnlySpan<char> topLevel, ReadOnlySpan<char> subtype) =>
+        (topLevel.Equals("application", StringComparison.OrdinalIgnoreCase) && (
+            subtype.Equals("pdf", StringComparison.OrdinalIgnoreCase) ||
+            subtype.Equals("msword", StringComparison.OrdinalIgnoreCase) ||
+            subtype.Equals("rtf", StringComparison.OrdinalIgnoreCase) ||
+            subtype.StartsWith("vnd.openxmlformats-officedocument", StringComparison.OrdinalIgnoreCase) ||
+            subtype.StartsWith("vnd.ms-excel", StringComparison.OrdinalIgnoreCase) ||
+            subtype.StartsWith("vnd.ms-powerpoint", StringComparison.OrdinalIgnoreCase) ||
+            subtype.StartsWith("vnd.oasis.opendocument", StringComparison.OrdinalIgnoreCase))) ||
+        (topLevel.Equals("text", StringComparison.OrdinalIgnoreCase) &&
+            subtype.Equals("rtf", StringComparison.OrdinalIgnoreCase));
+
     /// <summary>Extracts code text from code interpreter inputs.</summary>
     /// <remarks>
     /// Code interpreter inputs typically contain a DataContent with a "text/x-python" or similar
diff --git a/src/Libraries/Microsoft.Extensions.AI/Embeddings/OpenTelemetryEmbeddingGenerator.cs b/src/Libraries/Microsoft.Extensions.AI/Embeddings/OpenTelemetryEmbeddingGenerator.cs
index 090332b255f..78176cb3f25 100644
--- a/src/Libraries/Microsoft.Extensions.AI/Embeddings/OpenTelemetryEmbeddingGenerator.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/Embeddings/OpenTelemetryEmbeddingGenerator.cs
@@ -18,7 +18,7 @@ namespace Microsoft.Extensions.AI;
 
 /// <summary>Represents a delegating embedding generator that implements the OpenTelemetry Semantic Conventions for Generative AI systems.</summary>
 /// <remarks>
-/// This class provides an implementation of the Semantic Conventions for Generative AI systems v1.41, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
+/// This class provides an implementation of the GenAI Semantic Conventions latest, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
 /// The specification is still experimental and subject to change; as such, the telemetry output by this client is also subject to change.
 /// </remarks>
 /// <typeparam name="TInput">The type of input used to produce embeddings.</typeparam>
diff --git a/src/Libraries/Microsoft.Extensions.AI/OpenTelemetryConsts.cs b/src/Libraries/Microsoft.Extensions.AI/OpenTelemetryConsts.cs
index 804d0d9f684..f594c7a7dcf 100644
--- a/src/Libraries/Microsoft.Extensions.AI/OpenTelemetryConsts.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/OpenTelemetryConsts.cs
@@ -126,6 +126,7 @@ public static class Request
             public const string Model = "gen_ai.request.model";
             public const string MaxTokens = "gen_ai.request.max_tokens";
             public const string PresencePenalty = "gen_ai.request.presence_penalty";
+            public const string ReasoningLevel = "gen_ai.request.reasoning.level";
             public const string Seed = "gen_ai.request.seed";
             public const string StopSequences = "gen_ai.request.stop_sequences";
             public const string Stream = "gen_ai.request.stream";
diff --git a/src/Libraries/Microsoft.Extensions.AI/Realtime/OpenTelemetryRealtimeClientSession.cs b/src/Libraries/Microsoft.Extensions.AI/Realtime/OpenTelemetryRealtimeClientSession.cs
index a7f78f9e9a6..3d13dd18c40 100644
--- a/src/Libraries/Microsoft.Extensions.AI/Realtime/OpenTelemetryRealtimeClientSession.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/Realtime/OpenTelemetryRealtimeClientSession.cs
@@ -24,7 +24,7 @@ namespace Microsoft.Extensions.AI;
 /// <summary>Represents a delegating realtime session that follows the OpenTelemetry Semantic Conventions for Generative AI systems where applicable.</summary>
 /// <remarks>
 /// <para>
-/// This class follows the patterns of the Semantic Conventions for Generative AI systems v1.41 where applicable, as defined at
+/// This class follows the patterns of the GenAI Semantic Conventions latest where applicable, as defined at
 /// <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />, with custom extensions for realtime-specific behavior.
 /// The specification does not currently define a realtime operation; a custom operation name is used.
 /// </para>
diff --git a/src/Libraries/Microsoft.Extensions.AI/SpeechToText/OpenTelemetrySpeechToTextClient.cs b/src/Libraries/Microsoft.Extensions.AI/SpeechToText/OpenTelemetrySpeechToTextClient.cs
index 82ece57f673..6e4cb490f2b 100644
--- a/src/Libraries/Microsoft.Extensions.AI/SpeechToText/OpenTelemetrySpeechToTextClient.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/SpeechToText/OpenTelemetrySpeechToTextClient.cs
@@ -22,7 +22,7 @@ namespace Microsoft.Extensions.AI;
 
 /// <summary>Represents a delegating speech-to-text client that implements the OpenTelemetry Semantic Conventions for Generative AI systems.</summary>
 /// <remarks>
-/// This class provides an implementation of the Semantic Conventions for Generative AI systems v1.41, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
+/// This class provides an implementation of the GenAI Semantic Conventions latest, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
 /// The specification is still experimental and subject to change; as such, the telemetry output by this client is also subject to change.
 /// </remarks>
 [Experimental(DiagnosticIds.Experiments.AISpeechToText, UrlFormat = DiagnosticIds.UrlFormat)]
diff --git a/src/Libraries/Microsoft.Extensions.AI/TextToSpeech/OpenTelemetryTextToSpeechClient.cs b/src/Libraries/Microsoft.Extensions.AI/TextToSpeech/OpenTelemetryTextToSpeechClient.cs
index 3cf4eed611d..feba4c96cc0 100644
--- a/src/Libraries/Microsoft.Extensions.AI/TextToSpeech/OpenTelemetryTextToSpeechClient.cs
+++ b/src/Libraries/Microsoft.Extensions.AI/TextToSpeech/OpenTelemetryTextToSpeechClient.cs
@@ -21,7 +21,7 @@ namespace Microsoft.Extensions.AI;
 
 /// <summary>Represents a delegating text-to-speech client that implements the OpenTelemetry Semantic Conventions for Generative AI systems.</summary>
 /// <remarks>
-/// This class provides an implementation of the Semantic Conventions for Generative AI systems v1.41, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
+/// This class provides an implementation of the GenAI Semantic Conventions latest, defined at <see href="https://opentelemetry.io/docs/specs/semconv/gen-ai/" />.
 /// The specification is still experimental and subject to change; as such, the telemetry output by this client is also subject to change.
 /// </remarks>
 [Experimental(DiagnosticIds.Experiments.AITextToSpeech, UrlFormat = DiagnosticIds.UrlFormat)]
diff --git a/test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/OpenTelemetryChatClientTests.cs b/test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/OpenTelemetryChatClientTests.cs
index 6ef724f7c66..db573f72a35 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/OpenTelemetryChatClientTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/OpenTelemetryChatClientTests.cs
@@ -127,6 +127,7 @@ async static IAsyncEnumerable<ChatResponseUpdate> CallbackAsync(
             TopP = 4.0f,
             TopK = 7,
             PresencePenalty = 5.0f,
+            Reasoning = new ReasoningOptions { Effort = ReasoningEffort.Low },
             ResponseFormat = ChatResponseFormat.Json,
             Temperature = 6.0f,
             Seed = 42,
@@ -179,6 +180,7 @@ async static IAsyncEnumerable<ChatResponseUpdate> CallbackAsync(
         Assert.Equal(6.0f, activity.GetTagItem("gen_ai.request.temperature"));
         Assert.Equal(7, activity.GetTagItem("gen_ai.request.top_k"));
         Assert.Equal(123, activity.GetTagItem("gen_ai.request.max_tokens"));
+        Assert.Equal("low", activity.GetTagItem("gen_ai.request.reasoning.level"));
         Assert.Equal("""["hello", "world"]""", activity.GetTagItem("gen_ai.request.stop_sequences"));
         Assert.Equal(enableSensitiveData ? "value1" : null, activity.GetTagItem("service_tier"));
         Assert.Equal(enableSensitiveData ? "value2" : null, activity.GetTagItem("SomethingElse"));
@@ -445,6 +447,8 @@ async static IAsyncEnumerable<ChatResponseUpdate> CallbackAsync(
                 new TextReasoningContent("User reasoning"),
                 new DataContent(Convert.FromBase64String("ZGF0YSBjb250ZW50"), "audio/mp3"),
                 new UriContent(new Uri("https://example.com/video.mp4"), "video/mp4"),
+                new DataContent(Convert.FromBase64String("dGVzdA=="), "application/pdf"),
+                new UriContent(new Uri("https://example.com/report.docx"), "application/vnd.openxmlformats-officedocument.wordprocessingml.document"),
                 new HostedFileContent("file-xyz789"),
             ]),
             new(ChatRole.Assistant, [new FunctionCallContent("call-456", "SearchFiles")]),
@@ -493,8 +497,20 @@ async static IAsyncEnumerable<ChatResponseUpdate> CallbackAsync(
                     "modality": "video"
                   },
                   {
-                    "type": "file",
-                    "file_id": "file-xyz789"
+                   "type": "blob",
+                   "content": "dGVzdA==",
+                   "mime_type": "application/pdf",
+                   "modality": "document"
+                  },
+                  {
+                   "type": "uri",
+                   "uri": "https://example.com/report.docx",
+                   "mime_type": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+                   "modality": "document"
+                  },
+                  {
+                   "type": "file",
+                   "file_id": "file-xyz789"
                   }
                 ]
               },