.NET: Connecting to 'grok' models in Azure Foundry

[Dazfl]

Hi all,

Has anyone successfully connected to any 'grok' model hosted in Azure Foundry using the agent framework? I've tried, but I am getting the following error message: Service request failed. Status: 422 (Unprocessable Entity).

The code I'm using to connect to this model is (the important bits):

var azureChatClient = new AzureOpenAIClient(endpoint: new Uri("https://<resource>.cognitiveservices.azure.com/"), credential: new AzureKeyCredential(key), options: clientOptions);

var agent = azureChatClient.GetChatClient("grok-4-fast-reasoning")
                .AsIChatClient()
                .AsBuilder()
                    .UseOpenTelemetry(configure: config => config.EnableSensitiveData = true)
                    .UseFunctionInvocation()
                .BuildAIAgent(new ChatClientAgentOptions()
                {
                    Name = agentName,
                    Description = agentDescription,
                    ChatOptions = new ChatOptions()
                    {
                        Instructions = instructions,
                        Tools = toolList,
                        ResponseFormat = ChatResponseFormat.ForJsonSchema<AgentStructuredResponse>(),
                        Reasoning = new ReasoningOptions() { Effort = ReasoningEffort.High, Output = ReasoningOutput.None }
                    },
                    ChatHistoryProviderFactory = async (ctx, ct) => new InMemoryChatHistoryProvider(new MessageCountingChatReducer(10), ctx.SerializedState, ctx.JsonSerializerOptions, InMemoryChatHistoryProvider.ChatReducerTriggerEvent.AfterMessageAdded)
                },
                services: serviceProvider);

This agent is then executed as a tool from another agent using the following code:

var response = await agent.RunAsync<AgentStructuredResponse>(query);  // --> error here

BTW, the only way I've been able to connect to model in Foundry is to use the congnitiveservices url. I've tried https://<resource>.services.ai.azure.com/openai/v1/ but I keep getting a 404 Resource not found error.

If anyone has been able to successfully connect to 'grok' models, what am I missing?

UPDATE: I've since worked out that the endpoint url should just be - https://<resource>.services.ai.azure.com/. This works when connecting to GPT models, but I'm still getting the original error when connecting to a 'grok' model.

UPDATE 2: I've narrowed the issue down to the tools. I removed the tools and the model worked. Maybe this is a bug.

[Dazfl]

Ok, I've worked it out. The tools cannot have a '.' in the name - for example 'tool.name'. It can have a hyphen ('tool-name').

This is what was causing the error.