braintrustdata · Brendan Gooden (brendangooden) · Apr 13, 2026 · Apr 13, 2026
diff --git a/Directory.Build.targets b/Directory.Build.targets
@@ -94,7 +94,7 @@
   </PropertyGroup>
 
   <!-- Target to verify the version in the built assembly matches the expected git version -->
-  <Target Name="VerifyAssemblyVersion" AfterTargets="Build" Condition="'$(MSBuildProjectName)' == 'Braintrust.Sdk' or '$(MSBuildProjectName)' == 'Braintrust.Sdk.OpenAI' or '$(MSBuildProjectName)' == 'Braintrust.Sdk.Anthropic'">
+  <Target Name="VerifyAssemblyVersion" AfterTargets="Build" Condition="'$(SkipVersionVerification)' != 'true' and ('$(MSBuildProjectName)' == 'Braintrust.Sdk' or '$(MSBuildProjectName)' == 'Braintrust.Sdk.OpenAI' or '$(MSBuildProjectName)' == 'Braintrust.Sdk.Anthropic')">
     <Message Text="Verifying SDK version in built assembly..." Importance="high" />
 
     <!-- Get the expected version (recompute it to ensure consistency) -->

diff --git a/README.md b/README.md
@@ -9,7 +9,7 @@ This library provides tools for **evaluating** and **tracing** AI applications i
 
 - **Evaluate** your AI models with custom test cases and scoring functions
 - **Trace** LLM calls and monitor AI application performance with OpenTelemetry
-- **Integrate** seamlessly with OpenAI, Anthropic, Microsoft Agent Framework, and other LLM providers
+- **Integrate** seamlessly with OpenAI, Anthropic, Microsoft Agent Framework, Microsoft.Extensions.AI (IChatClient), and other LLM providers
 
 This SDK is currently in BETA status and APIs may change.
 
@@ -35,20 +35,31 @@ dotnet add package Braintrust.Sdk.OpenAI
 dotnet add package Braintrust.Sdk.Anthropic
 ```
 
+### Microsoft.Extensions.AI integration (IChatClient)
+
+```bash
+dotnet add package Braintrust.Sdk.Extensions.AI
+```
+
+Works with any `IChatClient` provider: OpenAI, Azure OpenAI, Ollama, etc.
+
 ### Microsoft Agent Framework integration
 
 ```bash
 dotnet add package Braintrust.Sdk.AgentFramework
 ```
 
+For agent orchestration with `ChatClientAgent`. Includes IChatClient + agent-level tracing.
+
 ### Or add to your .csproj file
 
 ```xml
 <ItemGroup>
   <PackageReference Include="Braintrust.Sdk" Version="version goes here" />
-  <PackageReference Include="Braintrust.Sdk.OpenAI" Version="version goes here" />          <!-- optional -->
-  <PackageReference Include="Braintrust.Sdk.Anthropic" Version="version goes here" />        <!-- optional -->
-  <PackageReference Include="Braintrust.Sdk.AgentFramework" Version="version goes here" />   <!-- optional -->
+  <PackageReference Include="Braintrust.Sdk.Extensions.AI" Version="version goes here" />    <!-- IChatClient -->
+  <PackageReference Include="Braintrust.Sdk.OpenAI" Version="version goes here" />           <!-- raw OpenAI SDK -->
+  <PackageReference Include="Braintrust.Sdk.Anthropic" Version="version goes here" />        <!-- raw Anthropic SDK -->
+  <PackageReference Include="Braintrust.Sdk.AgentFramework" Version="version goes here" />   <!-- Agent Framework -->
 </ItemGroup>
 ```
 

diff --git a/examples/ExtensionsAIInstrumentation/ExtensionsAIInstrumentation.csproj b/examples/ExtensionsAIInstrumentation/ExtensionsAIInstrumentation.csproj
@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\Braintrust.Sdk\Braintrust.Sdk.csproj" />
+    <ProjectReference Include="..\..\src\Braintrust.Sdk.Extensions.AI\Braintrust.Sdk.Extensions.AI.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.AI.OpenAI" Version="10.4.1" />
+    <PackageReference Include="OpenAI" Version="2.9.1" />
+  </ItemGroup>
+
+</Project>
diff --git a/examples/ExtensionsAIInstrumentation/Program.cs b/examples/ExtensionsAIInstrumentation/Program.cs
@@ -0,0 +1,72 @@
+using Braintrust.Sdk;
+using Braintrust.Sdk.Extensions.AI;
+using Microsoft.Extensions.AI;
+
+namespace Braintrust.Sdk.Examples.ExtensionsAIInstrumentation;
+
+/// <summary>
+/// Example demonstrating Braintrust instrumentation via Microsoft.Extensions.AI IChatClient.
+/// Works with any provider: OpenAI, Azure OpenAI, Ollama, etc.
+///
+/// Spans emitted include both braintrust.* (for Braintrust dashboard) and gen_ai.*
+/// (OTEL GenAI semantic conventions) attributes.
+/// </summary>
+class Program
+{
+    static async Task Main(string[] args)
+    {
+        var openAIApiKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY");
+        if (string.IsNullOrEmpty(openAIApiKey))
+        {
+            Console.WriteLine("ERROR: OPENAI_API_KEY environment variable not set. Bailing.");
+            return;
+        }
+
+        var braintrust = Braintrust.Get();
+        var activitySource = braintrust.GetActivitySource();
+
+        // Create an IChatClient from any provider — here using OpenAI via M.E.AI adapter
+        var openAIClient = new OpenAI.OpenAIClient(openAIApiKey);
+        IChatClient chatClient = openAIClient.GetChatClient("gpt-4o-mini").AsIChatClient();
+
+        // Add Braintrust tracing at both LLM and function levels
+        var tracedClient = new ChatClientBuilder(chatClient)
+            .UseAllBraintrustTracing(activitySource)
+            .Build();
+
+        // Define a tool
+        var getWeather = AIFunctionFactory.Create(
+            (string city) => $"The weather in {city} is sunny, 72°F.",
+            "GetWeather",
+            "Gets the current weather for a city.");
+
+        using (var rootActivity = activitySource.StartActivity("extensions-ai-instrumentation-example"))
+        {
+            if (rootActivity != null)
+            {
+                Console.WriteLine("~~~ EXTENSIONS.AI INSTRUMENTATION EXAMPLE\n");
+
+                // Non-streaming call with tool use
+                var response = await tracedClient.GetResponseAsync(
+                    [new ChatMessage(ChatRole.User, "What's the weather like in Seattle?")],
+                    new ChatOptions { Tools = [getWeather] });
+
+                Console.WriteLine($"Response: {response.Text}");
+
+                // Streaming call
+                Console.Write("\nStreaming: ");
+                await foreach (var update in tracedClient.GetStreamingResponseAsync(
+                    [new ChatMessage(ChatRole.User, "Tell me a joke.")]))
+                {
+                    Console.Write(update.Text);
+                }
+                Console.WriteLine();
+
+                // Print Braintrust link
+                var url = await braintrust.GetProjectUriAsync()
+                    + $"/logs?r={rootActivity.TraceId}&s={rootActivity.SpanId}";
+                Console.WriteLine($"\n  View your trace in Braintrust: {url}\n");
+            }
+        }
+    }
+}
diff --git a/src/Braintrust.Sdk.AgentFramework/BraintrustFunctionMiddleware.cs b/src/Braintrust.Sdk.AgentFramework/BraintrustFunctionMiddleware.cs
@@ -35,7 +35,9 @@ internal static class BraintrustFunctionMiddleware
                 if (activity != null)
                 {
                     SpanTagHelper.SetSpanType(activity, "function_call");
+                    activity.SetTag("gen_ai.operation.name", "execute_tool");
                     activity.SetTag("function.name", functionName);
+                    activity.SetTag("gen_ai.tool.name", functionName);
                     activity.SetTag("function.iteration", context.Iteration);
                     activity.SetTag("function.call_index", context.FunctionCallIndex);
                     activity.SetTag("function.total_count", context.FunctionCount);
@@ -44,8 +46,9 @@ internal static class BraintrustFunctionMiddleware
                     {
                         try
                         {
-                            activity.SetTag("braintrust.input_json",
-                                SpanTagHelper.ToJson(context.Arguments));
+                            var argsJson = SpanTagHelper.ToJson(context.Arguments);
+                            activity.SetTag("braintrust.input_json", argsJson);
+                            activity.SetTag("gen_ai.tool.call.arguments", argsJson);
                         }
                         catch
                         {
@@ -75,8 +78,9 @@ internal static class BraintrustFunctionMiddleware
                     {
                         try
                         {
-                            activity.SetTag("braintrust.output_json",
-                                SpanTagHelper.ToJson(new { result }));
+                            var resultJson = SpanTagHelper.ToJson(new { result });
+                            activity.SetTag("braintrust.output_json", resultJson);
+                            activity.SetTag("gen_ai.tool.call.result", resultJson);
                         }
                         catch
                         {

diff --git a/src/Braintrust.Sdk.Anthropic/InstrumentedMessageService.cs b/src/Braintrust.Sdk.Anthropic/InstrumentedMessageService.cs
@@ -166,12 +166,12 @@ public async IAsyncEnumerable<RawMessageStreamEvent> CreateStreaming(
                 activity.SetTag("braintrust.metrics.time_to_first_token", timeToFirstToken.Value);
             }
 
-            activity.SetTag(
-                "braintrust.output_json",
-                ToJson(new object[]
-                {
-                    new { role = role ?? "assistant", content = output.ToString() }
-                }));
+            var outputJson = ToJson(new object[]
+            {
+                new { role = role ?? "assistant", content = output.ToString() }
+            });
+            activity.SetTag("braintrust.output_json", outputJson);
+            activity.SetTag("gen_ai.output.messages", outputJson);
         }
     }
 
@@ -203,6 +203,8 @@ private static void TagActivity(
         double? timeToFirstToken = null)
     {
         activity.SetTag("provider", "anthropic");
+        activity.SetTag("gen_ai.operation.name", "chat");
+        activity.SetTag("gen_ai.provider.name", "anthropic");
         activity.SetTag("gen_ai.request.model", request.Model.Raw());
         activity.SetTag("gen_ai.response.model", response.Model.Raw());
 
@@ -221,14 +223,19 @@ private static void TagActivity(
                 sys.TryPickString(out var sysContent);
                 inputMessages.Add(new { role = "system", content = sysContent });
             }
-            activity.SetTag("braintrust.input_json", ToJson(inputMessages));
+            var inputJson = ToJson(inputMessages);
+            activity.SetTag("braintrust.input_json", inputJson);
+            activity.SetTag("gen_ai.input.messages", inputJson);
 
             var contentJson = response.ToString();
             activity.SetTag("braintrust.output_json", contentJson);
+            activity.SetTag("gen_ai.output.messages", contentJson);
 
             // Extract token usage metrics
             activity.SetTag("braintrust.metrics.prompt_tokens", response.Usage.InputTokens);
+            activity.SetTag("gen_ai.usage.input_tokens", response.Usage.InputTokens);
             activity.SetTag("braintrust.metrics.completion_tokens", response.Usage.OutputTokens);
+            activity.SetTag("gen_ai.usage.output_tokens", response.Usage.OutputTokens);
             activity.SetTag("braintrust.metrics.tokens", response.Usage.InputTokens + response.Usage.OutputTokens);
 
             if (timeToFirstToken is > 0)
@@ -259,12 +266,15 @@ private static void TagStreamActivity(Activity activity, MessageCreateParams req
     {
         activity.SetTag("stream", true);
         activity.SetTag("provider", "anthropic");
+        activity.SetTag("gen_ai.operation.name", "chat");
+        activity.SetTag("gen_ai.provider.name", "anthropic");
         activity.SetTag("gen_ai.request.model", request.Model.Raw());
 
         try
         {
             var messagesJson = ToJson(request.Messages);
             activity.SetTag("braintrust.input_json", messagesJson);
+            activity.SetTag("gen_ai.input.messages", messagesJson);
         }
         catch
         {

diff --git a/src/Braintrust.Sdk.Extensions.AI/Braintrust.Sdk.Extensions.AI.csproj b/src/Braintrust.Sdk.Extensions.AI/Braintrust.Sdk.Extensions.AI.csproj
@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <!-- Version is determined dynamically from git state in Directory.Build.targets -->
+    <PackageReadmeFile>README.md</PackageReadmeFile>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <InternalsVisibleTo Include="Braintrust.Sdk.Extensions.AI.Tests" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Include="README.md" Pack="true" PackagePath="\" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Braintrust.Sdk\Braintrust.Sdk.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.AI" Version="10.4.1" />
+  </ItemGroup>
+
+</Project>