Address PR feedback: simplify TryGetOuterToolExecutionActivity, remove comments, use pattern matching

- Invert if statement in TryGetOuterToolExecutionActivity to avoid multiple return false
- Remove "Per MCP" comment in McpSessionHandler
- Use pattern matching `is "tcp"` instead of `== "tcp"`
- Remove redundant DisplayName setting (StartActivity already sets it via CreateActivityName)

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Diagnostics.cs

@@ -105,15 +105,10 @@ internal static bool ShouldInstrumentMessage(JsonRpcMessage message) =>
     /// <returns>true if an outer tool execution activity was found and can be reused; false otherwise.</returns>
     internal static bool TryGetOuterToolExecutionActivity([NotNullWhen(true)] out Activity? activity)
     {
-        activity = Activity.Current;
-        if (activity is null)
-        {
-            return false;
-        }
-
-        // Check if the current activity name indicates a tool execution (e.g., "execute_tool toolName")
-        if (activity.OperationName.StartsWith("execute_tool ", StringComparison.Ordinal))
+        if (Activity.Current is { } currentActivity &&
+            currentActivity.OperationName.StartsWith("execute_tool ", StringComparison.Ordinal))
         {
+            activity = currentActivity;
             return true;
         }
 

src/ModelContextProtocol.Core/McpSessionHandler.cs

@@ -84,8 +84,6 @@ public McpSessionHandler(
     {
         Throw.IfNull(transport);
 
-        // Per MCP semantic conventions: "pipe" for stdio, "tcp" or "quic" for HTTP
-        // https://github.com/open-telemetry/semantic-conventions/blob/main/docs/gen-ai/mcp.md#recording-mcp-transport
         _transportKind = transport switch
         {
             StdioClientSessionTransport or StdioServerTransport => "pipe",
@@ -666,7 +664,7 @@ private void AddTags(ref TagList tags, Activity? activity, JsonRpcMessage messag
         tags.Add("mcp.method.name", method);
         tags.Add("network.transport", _transportKind);
 
-        if (_transportKind == "tcp")
+        if (_transportKind is "tcp")
         {
             tags.Add("network.protocol.name", "http");
         }
@@ -684,11 +682,6 @@ private void AddTags(ref TagList tags, Activity? activity, JsonRpcMessage messag
             {
                 activity.AddTag("jsonrpc.request.id", withId.Id.Id?.ToString());
             }
-
-            if (!usingOuterActivity && target is not null)
-            {
-                activity.DisplayName = $"{method} {target}";
-            }
         }
 
         switch (method)