Move ToolCallCompleted log after IsError check in task path

Address code review: only log ToolCallCompleted when the task-augmented
tool execution result indicates success (not IsError).

Co-authored-by: halter73 <54385+halter73@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Server/McpServerImpl.cs

@@ -1009,11 +1009,15 @@ private async ValueTask<CallToolResult> ExecuteToolAsTaskAsync(
 
                 // Invoke the tool with task-specific cancellation token
                 var result = await tool.InvokeAsync(request, taskCancellationToken).ConfigureAwait(false);
-                ToolCallCompleted(request.Params?.Name ?? string.Empty);
 
                 // Determine final status based on whether there was an error
                 var finalStatus = result.IsError is true ? McpTaskStatus.Failed : McpTaskStatus.Completed;
 
+                if (finalStatus == McpTaskStatus.Completed)
+                {
+                    ToolCallCompleted(request.Params?.Name ?? string.Empty);
+                }
+
                 // Store the result (serialize to JsonElement)
                 var resultElement = JsonSerializer.SerializeToElement(result, McpJsonUtilities.JsonContext.Default.CallToolResult);
                 var finalTask = await taskStore.StoreTaskResultAsync(