Fix servicebus error propagation

[g2vinay]

Fixes the issue where missing parameter wasn't being propagated in the response to the LLM.

[Copilot]

Pull request overview

Improves error propagation to the LLM when tool invocations fail due to missing required parameters, and adds Service Bus command unit coverage for authentication failures.

Changes:

• Update tool-loader “missing required options” handling to surface the underlying error text (instead of a generic message).
• Add Service Bus unit tests to validate AuthenticationFailedException maps to 401 Unauthorized with the expected guidance message.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tools/Azure.Mcp.Tools.ServiceBus/tests/Azure.Mcp.Tools.ServiceBus.UnitTests/Topic/TopicDetailsCommandTests.cs	Adds auth-failure unit test for topic details command response/status/message.
tools/Azure.Mcp.Tools.ServiceBus/tests/Azure.Mcp.Tools.ServiceBus.UnitTests/Topic/SubscriptionDetailsCommandTests.cs	Adds auth-failure unit test for subscription details command response/status/message.
tools/Azure.Mcp.Tools.ServiceBus/tests/Azure.Mcp.Tools.ServiceBus.UnitTests/Queue/QueueDetailsCommandTests.cs	Adds auth-failure unit test for queue details command response/status/message.
core/Microsoft.Mcp.Core/src/Areas/Server/Commands/ToolLoading/ServerToolLoader.cs	Uses the child tool’s missing-options text in the guidance response.
core/Microsoft.Mcp.Core/src/Areas/Server/Commands/ToolLoading/NamespaceToolLoader.cs	Uses commandResponse.Message (with fallback) in the guidance response.

Comments suppressed due to low confidence (3)

core/Microsoft.Mcp.Core/src/Areas/Server/Commands/ToolLoading/ServerToolLoader.cs:296

• This change is intended to propagate the specific “Missing required options” message to the LLM, but there doesn’t appear to be unit coverage that asserts the final CallToolResult contains that propagated message (and only once). Please add/extend tool-loader tests (e.g., in core/Azure.Mcp.Core/.../ServerToolLoaderTests.cs) to simulate a child tool returning a TextContentBlock with “Missing required options …” and verify the constructed response includes that exact text and the tool spec guidance.

                if (textContent.Text.Contains("Missing required options", StringComparison.OrdinalIgnoreCase))
                {
                    var childToolSpecJson = await GetChildToolJsonAsync(request, tool, command, cancellationToken);

                    _logger.LogWarning("Tool {Tool} command {Command} requires additional parameters.", tool, command);
                    var finalResponse = new CallToolResult
                    {
                        Content =
                        [
                            new TextContentBlock {
                                    Text = $"""
                                        {textContent.Text}

                                        - Review the following command spec and identify the required arguments from the input schema.
                                        - Omit any arguments that are not required or do not apply to your use case.
                                        - Wrap all command arguments into the root "parameters" argument.
                                        - If required data is missing infer the data from your context or prompt the user as needed.
                                        - Run the tool again with the "command" and root "parameters" object.

                                        Command Spec:
                                        {childToolSpecJson}
                                        """

core/Microsoft.Mcp.Core/src/Areas/Server/Commands/ToolLoading/NamespaceToolLoader.cs:406

• The new errorMessage propagation path should be covered by a unit test to ensure commandResponse.Message (the specific missing-parameter details) is surfaced in the first text block returned to the LLM. Consider adding a NamespaceToolLoaderTests case that executes a command with missing required options and asserts the resulting CallToolResult.Content[0] starts with the original commandResponse.Message (not the generic fallback).

                _logger.LogWarning("Namespace {Namespace} command {Command} requires additional parameters.", namespaceName, command);
                
                // Extract the specific error message from the response
                var errorMessage = string.IsNullOrEmpty(commandResponse.Message) 
                    ? $"The '{command}' command is missing required parameters."
                    : commandResponse.Message;
                
                var finalResponse = new CallToolResult
                {
                    Content =
                    [
                        new TextContentBlock {
                                Text = $"""
                                    {errorMessage}

                                    - Review the following command spec and identify the required arguments from the input schema.
                                    - Omit any arguments that are not required or do not apply to your use case.
                                    - Wrap all command arguments into the root "parameters" argument.
                                    - If required data is missing infer the data from your context or prompt the user as needed.
                                    - Run the tool again with the "command" and root "parameters" object.

                                    Command Spec:
                                    {childToolSpecJson}
                                    """
                            }

core/Microsoft.Mcp.Core/src/Areas/Server/Commands/ToolLoading/ServerToolLoader.cs:304

• The new prompt prepends textContent.Text, but the code then appends all toolCallResponse.Content blocks (including the same TextContentBlock) to finalResponse.Content. This will duplicate the “Missing required options …” text in the final response content. Consider either not re-adding the original text block, or keep the append but change the prepended text to a short summary (or dedupe by reference/type).

                    var finalResponse = new CallToolResult
                    {
                        Content =
                        [
                            new TextContentBlock {
                                    Text = $"""
                                        {textContent.Text}

                                        - Review the following command spec and identify the required arguments from the input schema.
                                        - Omit any arguments that are not required or do not apply to your use case.
                                        - Wrap all command arguments into the root "parameters" argument.
                                        - If required data is missing infer the data from your context or prompt the user as needed.
                                        - Run the tool again with the "command" and root "parameters" object.

                                        Command Spec:
                                        {childToolSpecJson}
                                        """
                                }
                        ]
                    };

                    foreach (var contentBlock in toolCallResponse.Content)
                    {
                        finalResponse.Content.Add(contentBlock);
                    }