Fix foundry agents connect serialization bug

servers/Azure.Mcp.Server/CHANGELOG.md

@@ -10,6 +10,8 @@ The Azure MCP Server updates automatically by default whenever a new release com
 
 ### Bugs Fixed
 
+- Fixed a bug where agents connect command result including file search result fail with serialization error. [[#1205](https://github.com/microsoft/mcp/pull/1205)]
+
 ### Other Changes
 
 - Begin capturing information for the MCP client request's `_meta` store. [[#1154](https://github.com/microsoft/mcp/pull/1154)]

tools/Azure.Mcp.Tools.Foundry/src/Commands/FoundryJsonContext.cs

@@ -64,5 +64,6 @@ namespace Azure.Mcp.Tools.Foundry.Commands;
 [JsonSerializable(typeof(ThreadCreateResult))]
 [JsonSerializable(typeof(ThreadListResult))]
 [JsonSerializable(typeof(ThreadGetMessagesResult))]
+[JsonSerializable(typeof(List<AgentFileSearchResult>))]
 [JsonSourceGenerationOptions(PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase, DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingDefault)]
 internal sealed partial class FoundryJsonContext : JsonSerializerContext;

tools/Azure.Mcp.Tools.Foundry/src/Models/AgentFileSearchResult.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Text.Json.Serialization;
+using Azure.AI.Agents.Persistent;
+
+namespace Azure.Mcp.Tools.Foundry.Models;
+
+internal class AgentFileSearchResult
+{
+    [JsonPropertyName("fileId")]
+    public string? FileId { get; set; }
+
+    [JsonPropertyName("fileName")]
+    public string? FileName { get; set; }
+
+    [JsonPropertyName("score")]
+    public float Score { get; set; }
+
+    [JsonPropertyName("content")]
+    public IReadOnlyList<FileSearchToolCallContent>? Content { get; set; }
+}

tools/Azure.Mcp.Tools.Foundry/src/Services/FoundryService.cs

@@ -1257,26 +1257,10 @@ private List<ToolDefinitionAIFunction> ConvertToolDefinitionsFromString(string?
             {
                 foreach (RunStepToolCall toolCall in details.ToolCalls)
                 {
-                    Microsoft.Extensions.AI.ChatMessage CreateRequestMessage(string name, Dictionary<string, object?> arguments) =>
-                        new(ChatRole.Assistant, [new FunctionCallContent(toolCall.Id, name, arguments)])
-                        {
-                            AuthorName = step.AssistantId,
-                            MessageId = step.Id,
-                            RawRepresentation = step,
-                        };
-
-                    Microsoft.Extensions.AI.ChatMessage CreateResponseMessage(object result) =>
-                        new(ChatRole.Tool, [new FunctionResultContent(toolCall.Id, result)])
-                        {
-                            AuthorName = step.AssistantId,
-                            MessageId = step.Id,
-                            RawRepresentation = step,
-                        };
-
                     switch (toolCall)
                     {
                         case RunStepFunctionToolCall function:
-                            yield return CreateRequestMessage(function.Name, Parse(function.Arguments) ?? []);
+                            yield return CreateRequestMessage(toolCall.Id, function.Name, Parse(function.Arguments) ?? [], step);
                             // TODO: output doesn't appear to be available in the API
 
                             static Dictionary<string, object?>? Parse(string arguments)
@@ -1288,43 +1272,44 @@ Microsoft.Extensions.AI.ChatMessage CreateResponseMessage(object result) =>
                             break;
 
                         case RunStepCodeInterpreterToolCall code:
-                            yield return CreateRequestMessage("code_interpreter", new() { ["input"] = code.Input });
-                            yield return CreateResponseMessage(string.Concat(code.Outputs.OfType<RunStepCodeInterpreterLogOutput>().Select(o => o.Logs)));
+                            yield return CreateRequestMessage(toolCall.Id, "code_interpreter", new() { ["input"] = code.Input }, step);
+                            yield return CreateResponseMessage(toolCall.Id, string.Concat(code.Outputs.OfType<RunStepCodeInterpreterLogOutput>().Select(o => o.Logs)), step);
                             break;
 
                         case RunStepBingGroundingToolCall bing:
-                            yield return CreateRequestMessage("bing_grounding", new() { ["requesturl"] = bing.BingGrounding["requesturl"] });
+                            yield return CreateRequestMessage(toolCall.Id, "bing_grounding", new() { ["requesturl"] = bing.BingGrounding["requesturl"] }, step);
                             break;
 
                         case RunStepFileSearchToolCall fileSearch:
-                            yield return CreateRequestMessage("file_search", new()
+                            yield return CreateRequestMessage(toolCall.Id, "file_search", new()
                             {
                                 ["ranking_options"] = JsonSerializer.SerializeToElement(new()
                                 {
                                     ["ranker"] = fileSearch.FileSearch.RankingOptions.Ranker,
                                     ["score_threshold"] = fileSearch.FileSearch.RankingOptions.ScoreThreshold,
                                 }, DictionaryTypeInfo)
-                            });
-                            yield return CreateResponseMessage(fileSearch.FileSearch.Results.Select(r => new
+                            }, step);
+                            List<AgentFileSearchResult> fileSearchResults = fileSearch.FileSearch.Results.Select(r => new AgentFileSearchResult
                             {
-                                file_id = r.FileId,
-                                file_name = r.FileName,
-                                score = r.Score,
-                                content = r.Content,
-                            }).ToList());
+                                FileId = r.FileId,
+                                FileName = r.FileName,
+                                Score = r.Score,
+                                Content = r.Content,
+                            }).ToList();
+                            yield return CreateResponseMessage(toolCall.Id, fileSearchResults, step);
                             break;
 
                         case RunStepAzureAISearchToolCall aiSearch:
-                            yield return CreateRequestMessage("azure_ai_search", new() { ["input"] = aiSearch.AzureAISearch["input"] });
-                            yield return CreateResponseMessage(new Dictionary<string, object?>
+                            yield return CreateRequestMessage(toolCall.Id, "azure_ai_search", new() { ["input"] = aiSearch.AzureAISearch["input"] }, step);
+                            yield return CreateResponseMessage(toolCall.Id, new Dictionary<string, string?>
                             {
                                 ["output"] = aiSearch.AzureAISearch["output"]
-                            });
+                            }, step);
                             break;
 
                         case RunStepMicrosoftFabricToolCall fabric:
-                            yield return CreateRequestMessage("fabric_dataagent", new() { ["input"] = fabric.MicrosoftFabric["input"] });
-                            yield return CreateResponseMessage(fabric.MicrosoftFabric["output"]);
+                            yield return CreateRequestMessage(toolCall.Id, "fabric_dataagent", new() { ["input"] = fabric.MicrosoftFabric["input"] }, step);
+                            yield return CreateResponseMessage(toolCall.Id, fabric.MicrosoftFabric["output"], step);
                             break;
                     }
                 }
@@ -1688,4 +1673,54 @@ public string SerializeToolDefinition()
             return Encoding.UTF8.GetString(bytes.GetBuffer(), 0, (int)bytes.Length);
         }
     }
+
+    internal static Microsoft.Extensions.AI.ChatMessage CreateRequestMessage(string toolCallId, string name, Dictionary<string, object?> arguments, RunStep step)
+    {
+        return new(ChatRole.Assistant, [new FunctionCallContent(toolCallId, name, arguments)])
+        {
+            AuthorName = step.AssistantId,
+            MessageId = step.Id,
+            RawRepresentation = step,
+        };
+    }
+
+    internal static Microsoft.Extensions.AI.ChatMessage CreateResponseMessage(string toolCallId, List<AgentFileSearchResult> result, RunStep step)
+    {
+        return new(ChatRole.Tool, [new FunctionResultContent(toolCallId, result)])
+        {
+            AuthorName = step.AssistantId,
+            MessageId = step.Id,
+            RawRepresentation = step,
+        };
+    }
+
+    internal static Microsoft.Extensions.AI.ChatMessage CreateResponseMessage(string toolCallId, JsonElement result, RunStep step)
+    {
+        return new(ChatRole.Tool, [new FunctionResultContent(toolCallId, result)])
+        {
+            AuthorName = step.AssistantId,
+            MessageId = step.Id,
+            RawRepresentation = step,
+        };
+    }
+
+    internal static Microsoft.Extensions.AI.ChatMessage CreateResponseMessage(string toolCallId, string result, RunStep step)
+    {
+        return new(ChatRole.Tool, [new FunctionResultContent(toolCallId, result)])
+        {
+            AuthorName = step.AssistantId,
+            MessageId = step.Id,
+            RawRepresentation = step,
+        };
+    }
+
+    internal static Microsoft.Extensions.AI.ChatMessage CreateResponseMessage(string toolCallId, IDictionary<string, string?> result, RunStep step)
+    {
+        return new(ChatRole.Tool, [new FunctionResultContent(toolCallId, result)])
+        {
+            AuthorName = step.AssistantId,
+            MessageId = step.Id,
+            RawRepresentation = step,
+        };
+    }
 }