AgentGroupChat - Agent returning empty response

[joaooo]

Hello,
Im reaching out as an attempt to get some clarity and help in what's going on because i'm out of ideas and it might even be a silly thing.

I have implemented a AgentGroupChat with three agents: One as a 'Manager' to orchestrate the process, another one as 'DevOpsAgent' to take care of DevOps calls (such as download repo), lastly, a 'refactorAgent' that processes N files by refactoring each one of them. I also implemented my own MCP to try to simplify things as: Access to DevOps and file system operations.
The issue arrises sometimes but still +50% of the times, where one agent just starts returning empty string and seems to be stuck in a loop and nothing happens, for example:

[Manager]: DevOpsAgent, download repository cbe5dc3a-7a8e-4922-8c0f-76e22ecfd5bc
[12:27:33 INF] Function null-Function_5f6a53fc4c40480fad694c2309508c69 invoking.
  [TOOL CALL] .Function_5f6a53fc4c40480fad694c2309508c69
  [TOOL ARGS] _agent_=Manager, history=[
  {
    "Role": "user",
    "Content": "Refactor all code files in repository: cbe5dc3a-7a8e-4922-8c0f-76e22ecfd5bc"
  },
  {
    "Role": "assistant",
    "Name": "Manager",
    "Content": "DevOpsAgent, download repository cbe5dc3a-7a8e-4922-8c0f-76e22ecfd5bc"
  }
]

[SELECTION] ␦ DevOpsAgent
[12:27:40 INF] End processing HTTP request after 722.0098ms - 200
[DevOpsAgent]: <EMPTY MESSAGE>
  - Item Type: TextContent
  - Detail:
[DevOpsAgent]:

I'm using SemanticKernel 1.70.0 with Google Connector 1.70.0-alpha

My DI is as follows:

services.AddHttpClient("VertexAI")
    .AddStandardResilienceHandler(options =>
    {
        options.Retry.MaxRetryAttempts = 6;
        options.Retry.BackoffType = Polly.DelayBackoffType.Exponential;
        options.AttemptTimeout.Timeout = TimeSpan.FromMinutes(5);
        options.TotalRequestTimeout.Timeout = TimeSpan.FromMinutes(10);
        options.CircuitBreaker.SamplingDuration = TimeSpan.FromMinutes(11);
    });


var kernelBuilder = services.AddKernel();

kernelBuilder.Services.AddLogging(loggingBuilder =>
{
    loggingBuilder.AddConsole().SetMinimumLevel(LogLevel.Trace);
});

var clientTransport = new HttpClientTransport(new HttpClientTransportOptions
{
    Endpoint = new Uri("http://localhost:5251")
});
var client = McpClient.CreateAsync(clientTransport).Result;

var tools = client.ListToolsAsync().Result;
foreach (var tool in tools)
{
    Console.WriteLine($"Registering tool: {tool.Name} - {tool.Description}");
}

var listFilesTool = tools.Where(t => t.Name == "list_files");
kernelBuilder.Plugins.AddFromFunctions("test", listFilesTool.Select(t => t.AsKernelFunction()));
kernelBuilder.Plugins.AddFromFunctions("MCPTools", tools.Select(t => t.AsKernelFunction()));


kernelBuilder.Services.AddSingleton<IFunctionInvocationFilter, ToolCallLoggingFilter>();
kernelBuilder.Services.AddSingleton<IAutoFunctionInvocationFilter, AutoFunctionCallLoggingFilter>();
kernelBuilder.Services.AddSingleton<IPromptRenderFilter, PromptLoggingFilter>();

kernelBuilder.Services.AddKeyedSingleton<IChatCompletionService>(null, (sp, key) =>
{
    var secretClient = sp.GetRequiredService<SecretClient>();
    var secret = secretClient.GetSecret("VertexAIThings");
    var serviceAccount = GoogleCredential.FromJson(secret.Value.Value).CreateScoped("https://www.googleapis.com/auth/cloud-platform");

    var httpClientFactory = sp.GetRequiredService<IHttpClientFactory>();
    var httpClient = httpClientFactory.CreateClient("VertexAI");


    return new VertexAIGeminiChatCompletionService(
        modelId: modelId,
        projectId: projectId,
        location: vertexAiLocation,
        httpClient: httpClient,
        bearerTokenProvider: async () =>
        {
            return await serviceAccount.UnderlyingCredential.GetAccessTokenForRequestAsync();
        });
});

In the beginning i only had one plugin which contained all the tools (devops & filesystem), but as the iterations went by, i tried filtering them out for those specific agents aswell.

 var strategyKernel = kernel.Clone();
        strategyKernel.Plugins.Remove(strategyKernel.Plugins["MCPTools"]);
        strategyKernel.Plugins.Remove(strategyKernel.Plugins["test"]);

        var managerKernel = kernel.Clone();
        managerKernel.Plugins.Remove(managerKernel.Plugins["MCPTools"]);

        var manager = AgentFactory.CreateManagerAgent(managerKernel);
        var devOpsAgent = AgentFactory.CreateDevOpsAgent(kernel.Clone());
        var refactorAgent = AgentFactory.CreateRefactorAgent(kernel.Clone());

#pragma warning disable SKEXP0110
        var chat = new AgentGroupChat(manager, devOpsAgent, refactorAgent)
        {
            ExecutionSettings = new AgentGroupChatSettings
            {
                SelectionStrategy = StrategyFactory.CreateSelectionStrategy(
                    strategyKernel, manager, devOpsAgent, refactorAgent),
                TerminationStrategy = StrategyFactory.CreateTerminationStrategy(
                    strategyKernel, manager, devOpsAgent, refactorAgent)
            }
        };

        chat.AddChatMessage(new ChatMessageContent(
            AuthorRole.User,
            $"Refactor all code files in repository: {request.repositoryId}"));

        await foreach (var message in chat.InvokeAsync(cancellationToken))
        {

            if (string.IsNullOrWhiteSpace(message.Content))
            {
                Console.WriteLine($"[{message.AuthorName}]: <EMPTY MESSAGE>");

                // Inspect items to confirm if this is an unhandled tool call
                if (message.Items?.Count > 0)
                {
                    foreach (var item in message.Items)
                    {
                        Console.WriteLine($"  - Item Type: {item.GetType().Name}");
                        Console.WriteLine($"  - Detail: {item}");
                    }
                }
            }

            Console.BackgroundColor = message.AuthorName switch
            {
                AgentFactory.ManagerName => ConsoleColor.Blue,
                AgentFactory.DevOpsAgentName => ConsoleColor.Green,
                AgentFactory.RefactorAgentName => ConsoleColor.Yellow,
                _ => ConsoleColor.Gray
            };
            Console.ForegroundColor = ConsoleColor.White;
            Console.WriteLine($"[{message.AuthorName}]: {message.Content?[..Math.Min(message.Content?.Length ?? 0, 500)]}");
            Console.ResetColor();
        }

My Strategy seems to be working fine, but i simply cant overcome this issue, can anyone point me in the right direction?
Thanks in advance

[moonbox3]

We would like to gently suggest for you to have a look at our predecessor framework - Microsoft Agent Framework - in place of SK's "Agent Framework" orchestrations: https://learn.microsoft.com/en-us/agent-framework/workflows/orchestrations/. GitHub repo is: https://github.com/microsoft/agent-framework