Give FunctionInvokingChatClient span a more OTELy name

src/Libraries/Microsoft.Extensions.AI/ChatCompletion/FunctionInvokingChatClient.cs

@@ -269,7 +269,7 @@ public override async Task<ChatResponse> GetResponseAsync(
 
         // A single request into this GetResponseAsync may result in multiple requests to the inner client.
         // Create an activity to group them together for better observability.
-        using Activity? activity = _activitySource?.StartActivity($"{nameof(FunctionInvokingChatClient)}.{nameof(GetResponseAsync)}");
+        using Activity? activity = _activitySource?.StartActivity(OpenTelemetryConsts.GenAI.OrchestrateToolsName);
 
         // Copy the original messages in order to avoid enumerating the original messages multiple times.
         // The IEnumerable can represent an arbitrary amount of work.
@@ -408,7 +408,7 @@ public override async IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseA
 
         // A single request into this GetStreamingResponseAsync may result in multiple requests to the inner client.
         // Create an activity to group them together for better observability.
-        using Activity? activity = _activitySource?.StartActivity($"{nameof(FunctionInvokingChatClient)}.{nameof(GetStreamingResponseAsync)}");
+        using Activity? activity = _activitySource?.StartActivity(OpenTelemetryConsts.GenAI.OrchestrateToolsName);
         UsageDetails? totalUsage = activity is { IsAllDataRequested: true } ? new() : null; // tracked usage across all turns, to be used for activity purposes
 
         // Copy the original messages in order to avoid enumerating the original messages multiple times.

src/Libraries/Microsoft.Extensions.AI/OpenTelemetryConsts.cs

@@ -35,6 +35,7 @@ public static class GenAI
         public const string ChatName = "chat";
         public const string EmbeddingsName = "embeddings";
         public const string ExecuteToolName = "execute_tool";
+        public const string OrchestrateToolsName = "orchestrate_tools"; // Non-standard
         public const string GenerateContentName = "generate_content";
 
         public const string SystemInstructions = "gen_ai.system_instructions";

test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/FunctionInvokingChatClientTests.cs

@@ -678,11 +678,11 @@ public async Task FunctionInvocationTrackedWithActivity(bool enableTelemetry, bo
         Func<ChatClientBuilder, ChatClientBuilder> configure = b => b.Use(c =>
             new FunctionInvokingChatClient(new OpenTelemetryChatClient(c, sourceName: sourceName) { EnableSensitiveData = enableSensitiveData }));
 
-        await InvokeAsync(() => InvokeAndAssertAsync(options, plan, configurePipeline: configure), streaming: false);
+        await InvokeAsync(() => InvokeAndAssertAsync(options, plan, configurePipeline: configure));
 
-        await InvokeAsync(() => InvokeAndAssertStreamingAsync(options, plan, configurePipeline: configure), streaming: true);
+        await InvokeAsync(() => InvokeAndAssertStreamingAsync(options, plan, configurePipeline: configure));
 
-        async Task InvokeAsync(Func<Task> work, bool streaming)
+        async Task InvokeAsync(Func<Task> work)
         {
             var activities = new List<Activity>();
             using TracerProvider? tracerProvider = enableTelemetry ?
@@ -700,7 +700,7 @@ async Task InvokeAsync(Func<Task> work, bool streaming)
                     activity => Assert.Equal("chat", activity.DisplayName),
                     activity => Assert.Equal("execute_tool Func1", activity.DisplayName),
                     activity => Assert.Equal("chat", activity.DisplayName),
-                    activity => Assert.Equal(streaming ? "FunctionInvokingChatClient.GetStreamingResponseAsync" : "FunctionInvokingChatClient.GetResponseAsync", activity.DisplayName));
+                    activity => Assert.Equal("orchestrate_tools", activity.DisplayName));
 
                 var executeTool = activities[1];
                 if (enableSensitiveData)