.NET: fix ChatCompletions Tools serialization

dotnet/src/Microsoft.Agents.AI.Hosting.OpenAI/ChatCompletions/Models/Tool.cs

@@ -18,7 +18,7 @@ internal abstract record Tool
     /// <summary>
     /// The type of the tool.
     /// </summary>
-    [JsonPropertyName("type")]
+    [JsonIgnore]
     public abstract string Type { get; }
 }
 
@@ -30,7 +30,7 @@ internal sealed record FunctionTool : Tool
     /// <summary>
     /// The type of the tool. Always "function".
     /// </summary>
-    [JsonPropertyName("type")]
+    [JsonIgnore]
     public override string Type => "function";
 
     /// <summary>
@@ -88,7 +88,7 @@ internal sealed record CustomTool : Tool
     /// <summary>
     /// The type of the tool. Always "custom".
     /// </summary>
-    [JsonPropertyName("type")]
+    [JsonIgnore]
     public override string Type => "custom";
 
     /// <summary>

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/ConformanceTraces/ChatCompletions/tools/request.json

@@ -0,0 +1,53 @@
+{
+  "model": "gpt-4o-mini",
+  "messages": [
+    {
+      "role": "user",
+      "content": "What's the weather like in San Francisco?"
+    }
+  ],
+  "max_completion_tokens": 256,
+  "temperature": 0.7,
+  "top_p": 1,
+  "tools": [
+    {
+      "type": "function",
+      "function": {
+        "name": "get_weather",
+        "description": "Get the current weather in a given location",
+        "parameters": {
+          "type": "object",
+          "properties": {
+            "location": {
+              "type": "string",
+              "description": "The city and state, e.g. San Francisco, CA"
+            },
+            "unit": {
+              "type": "string",
+              "enum": [ "celsius", "fahrenheit" ],
+              "description": "Temperature unit"
+            }
+          },
+          "required": [ "location" ]
+        }
+      }
+    },
+    {
+      "type": "function",
+      "function": {
+        "name": "get_time",
+        "description": "Get the current time in a given timezone",
+        "parameters": {
+          "type": "object",
+          "properties": {
+            "timezone": {
+              "type": "string",
+              "description": "The IANA timezone, e.g. America/Los_Angeles"
+            }
+          },
+          "required": [ "timezone" ]
+        }
+      }
+    }
+  ]
+}

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/ConformanceTraces/ChatCompletions/tools/response.json

@@ -0,0 +1,42 @@
+{
+  "id": "chatcmpl-tools-test-001",
+  "object": "chat.completion",
+  "created": 1234567890,
+  "model": "gpt-4o-mini",
+  "choices": [
+    {
+      "index": 0,
+      "message": {
+        "role": "assistant",
+        "content": null,
+        "tool_calls": [
+          {
+            "id": "call_abc123",
+            "type": "function",
+            "function": {
+              "name": "get_weather",
+              "arguments": "{\"location\": \"San Francisco, CA\", \"unit\": \"fahrenheit\"}"
+            }
+          }
+        ]
+      },
+      "finish_reason": "tool_calls"
+    }
+  ],
+  "usage": {
+    "prompt_tokens": 85,
+    "completion_tokens": 32,
+    "total_tokens": 117,
+    "prompt_tokens_details": {
+      "cached_tokens": 0,
+      "audio_tokens": 0
+    },
+    "completion_tokens_details": {
+      "reasoning_tokens": 0,
+      "audio_tokens": 0,
+      "accepted_prediction_tokens": 0,
+      "rejected_prediction_tokens": 0
+    }
+  },
+  "service_tier": "default"
+}

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests.csproj

@@ -27,16 +27,4 @@
     </None>
   </ItemGroup>
 
-  <ItemGroup>
-    <Content Remove="ConformanceTraces\ChatCompletions\function_calling\request.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\function_calling\response.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\json_mode\request.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\json_mode\response.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\multi_turn\request.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\multi_turn\response.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\streaming\request.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\system_message\request.json" />
-    <Content Remove="ConformanceTraces\ChatCompletions\system_message\response.json" />
-  </ItemGroup>
-
 </Project>

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/OpenAIChatCompletionsConformanceTests.cs

@@ -456,6 +456,136 @@ public async Task JsonModeRequestResponseAsync()
         Assert.Equal(JsonValueKind.String, jsonRoot.GetProperty("occupation").ValueKind);
     }
 
+    [Fact]
+    public async Task ToolsSerializationDeserializationAsync()
+    {
+        // Arrange
+        string requestJson = LoadChatCompletionsTraceFile("tools/request.json");
+        using var expectedResponseDoc = LoadChatCompletionsTraceDocument("tools/response.json");
+
+        HttpClient client = await this.CreateTestServerAsync(
+            "tools-agent",
+            "You are a helpful assistant with access to weather and time tools.",
+            "tool-call",
+            (msg) => [new FunctionCallContent("call_abc123", "get_weather", new Dictionary<string, object?>() {
+                { "location", "San Francisco, CA" },
+                { "unit", "fahrenheit" }
+            })]
+        );
+
+        // Act
+        HttpResponseMessage httpResponse = await this.SendChatCompletionRequestAsync(client, "tools-agent", requestJson);
+        using var responseDoc = await ParseResponseAsync(httpResponse);
+        var response = responseDoc.RootElement;
+
+        // Parse the request
+        using var requestDoc = JsonDocument.Parse(requestJson);
+        var request = requestDoc.RootElement;
+
+        // Assert - Request has tools array with proper structure
+        AssertJsonPropertyExists(request, "tools");
+        var tools = request.GetProperty("tools");
+        Assert.Equal(JsonValueKind.Array, tools.ValueKind);
+        Assert.Equal(2, tools.GetArrayLength());
+
+        // Assert - First tool (get_weather)
+        var weatherTool = tools[0];
+        AssertJsonPropertyEquals(weatherTool, "type", "function");
+        AssertJsonPropertyExists(weatherTool, "function");
+
+        var weatherFunction = weatherTool.GetProperty("function");
+        AssertJsonPropertyEquals(weatherFunction, "name", "get_weather");
+        AssertJsonPropertyExists(weatherFunction, "description");
+        AssertJsonPropertyExists(weatherFunction, "parameters");
+
+        var weatherParams = weatherFunction.GetProperty("parameters");
+        AssertJsonPropertyEquals(weatherParams, "type", "object");
+        AssertJsonPropertyExists(weatherParams, "properties");
+        AssertJsonPropertyExists(weatherParams, "required");
+
+        // Verify location property exists
+        var properties = weatherParams.GetProperty("properties");
+        AssertJsonPropertyExists(properties, "location");
+        AssertJsonPropertyExists(properties, "unit");
+
+        // Assert - Second tool (get_time)
+        var timeTool = tools[1];
+        AssertJsonPropertyEquals(timeTool, "type", "function");
+
+        var timeFunction = timeTool.GetProperty("function");
+        AssertJsonPropertyEquals(timeFunction, "name", "get_time");
+        AssertJsonPropertyExists(timeFunction, "description");
+        AssertJsonPropertyExists(timeFunction, "parameters");
+
+        // Assert - Response structure
+        AssertJsonPropertyExists(response, "id");
+        AssertJsonPropertyEquals(response, "object", "chat.completion");
+        AssertJsonPropertyExists(response, "created");
+        AssertJsonPropertyExists(response, "model");
+
+        // Assert - Response has tool_calls in choices
+        var choices = response.GetProperty("choices");
+        Assert.Equal(JsonValueKind.Array, choices.ValueKind);
+        Assert.True(choices.GetArrayLength() > 0);
+
+        var choice = choices[0];
+        AssertJsonPropertyExists(choice, "finish_reason");
+        AssertJsonPropertyEquals(choice, "finish_reason", anyOfValues: ["tool_calls", "stop"]);
+        AssertJsonPropertyExists(choice, "message");
+
+        var message = choice.GetProperty("message");
+        AssertJsonPropertyEquals(message, "role", "assistant");
+        AssertJsonPropertyExists(message, "tool_calls");
+
+        // Assert - Tool calls array structure
+        var toolCalls = message.GetProperty("tool_calls");
+        Assert.Equal(JsonValueKind.Array, toolCalls.ValueKind);
+        Assert.True(toolCalls.GetArrayLength() > 0);
+
+        var toolCall = toolCalls[0];
+        AssertJsonPropertyExists(toolCall, "id");
+        AssertJsonPropertyEquals(toolCall, "type", "function");
+        AssertJsonPropertyExists(toolCall, "function");
+
+        var callFunction = toolCall.GetProperty("function");
+        AssertJsonPropertyEquals(callFunction, "name", "get_weather");
+        AssertJsonPropertyExists(callFunction, "arguments");
+
+        // Assert - Tool call arguments are valid JSON
+        string arguments = callFunction.GetProperty("arguments").GetString()!;
+        using var argsDoc = JsonDocument.Parse(arguments);
+        var argsRoot = argsDoc.RootElement;
+        AssertJsonPropertyExists(argsRoot, "location");
+        AssertJsonPropertyEquals(argsRoot, "location", "San Francisco, CA");
+        AssertJsonPropertyEquals(argsRoot, "unit", "fahrenheit");
+
+        // Assert - Message content is null when tool_calls present
+        if (message.TryGetProperty("content", out var contentProp))
+        {
+            Assert.Equal(JsonValueKind.Null, contentProp.ValueKind);
+        }
+
+        // Assert - Usage statistics
+        AssertJsonPropertyExists(response, "usage");
+        var usage = response.GetProperty("usage");
+        AssertJsonPropertyExists(usage, "prompt_tokens");
+        AssertJsonPropertyExists(usage, "completion_tokens");
+        AssertJsonPropertyExists(usage, "total_tokens");
+
+        var promptTokens = usage.GetProperty("prompt_tokens").GetInt32();
+        var completionTokens = usage.GetProperty("completion_tokens").GetInt32();
+        var totalTokens = usage.GetProperty("total_tokens").GetInt32();
+
+        Assert.True(promptTokens > 0);
+        Assert.True(completionTokens > 0);
+        Assert.Equal(promptTokens + completionTokens, totalTokens);
+
+        // Assert - Service tier
+        AssertJsonPropertyExists(response, "service_tier");
+        var serviceTier = response.GetProperty("service_tier").GetString();
+        Assert.NotNull(serviceTier);
+    }
+
     /// <summary>
     /// Helper to parse chat completion chunks from SSE response.
     /// </summary>