Fix duplicate tools from OpenAI extra body

dotnet/src/Connectors/Connectors.OpenAI.UnitTests/Services/OpenAIChatCompletionExtraBodyTests.cs

@@ -117,6 +117,60 @@ public async Task ExtraBodyOverridesFirstClassPropertyAsync()
         Assert.Equal(0.0, body.GetProperty("temperature").GetDouble());
     }
 
+    [Theory]
+    [InlineData("tools")]
+    [InlineData("$.tools")]
+    public async Task ExtraBodyToolsDoesNotDuplicatePropertyAsync(string key)
+    {
+        // Arrange
+        var service = new OpenAIChatCompletionService("gpt-4o", apiKey: "NOKEY", httpClient: this._httpClient);
+        var settings = new OpenAIPromptExecutionSettings
+        {
+            ExtraBody = new Dictionary<string, object?>
+            {
+                [key] = new object[]
+                {
+                    new { type = "web_search" },
+                    new { type = "function", function = new { name = "lookup" } },
+                },
+            },
+        };
+
+        // Act
+        await service.GetChatMessageContentsAsync(this._chatHistory, settings);
+
+        // Assert
+        var body = ParseRequestBody(this._messageHandlerStub.RequestContent!);
+        var tools = Assert.Single(body.EnumerateObject(), property => property.NameEquals("tools"));
+        Assert.Equal("web_search", tools.Value[0].GetProperty("type").GetString());
+        Assert.Equal("function", tools.Value[1].GetProperty("type").GetString());
+        Assert.Equal("lookup", tools.Value[1].GetProperty("function").GetProperty("name").GetString());
+    }
+
+    [Fact]
+    public async Task ExtraBodyNestedToolsPathDoesNotDuplicatePropertyAsync()
+    {
+        // Arrange
+        var service = new OpenAIChatCompletionService("gpt-4o", apiKey: "NOKEY", httpClient: this._httpClient);
+        var settings = new OpenAIPromptExecutionSettings
+        {
+            ExtraBody = new Dictionary<string, object?>
+            {
+                ["$.tools[0].type"] = "web_search",
+            },
+        };
+
+        // Act
+        await service.GetChatMessageContentsAsync(this._chatHistory, settings);
+
+        // Assert
+        var body = ParseRequestBody(this._messageHandlerStub.RequestContent!);
+        var tools = Assert.Single(body.EnumerateObject(), property => property.NameEquals("tools"));
+        var tool = Assert.Single(tools.Value.EnumerateArray());
+        Assert.Equal("web_search", tool.GetProperty("type").GetString());
+        Assert.False(tool.TryGetProperty("function", out _));
+    }
+
     [Fact]
     public async Task ExtraBodyNestedDictionaryEmitsNestedJsonObjectAsync()
     {

dotnet/src/Connectors/Connectors.OpenAI/Settings/OpenAIPromptExecutionSettings.cs

@@ -650,6 +650,11 @@ protected override void PrepareChatOptionsForRequest(Microsoft.Extensions.AI.Cha
     /// </summary>
     internal static void ApplyExtraBodyEntry(ChatCompletionOptions options, string key, object? value)
     {
+        if (TryApplyExtraBodyTools(options, key, value))
+        {
+            return;
+        }
+
         string path = key.StartsWith("$.", StringComparison.Ordinal)
             ? key
             : $"$[{JsonSerializer.Serialize(key)}]";
@@ -669,6 +674,128 @@ internal static void ApplyExtraBodyEntry(ChatCompletionOptions options, string k
 #pragma warning restore SCME0001
     }
 
+    private static bool TryApplyExtraBodyTools(ChatCompletionOptions options, string key, object? value)
+    {
+        if (key is "tools" or "$.tools")
+        {
+            if (value is null)
+            {
+                return false;
+            }
+
+            JsonElement tools = JsonSerializer.SerializeToElement(value, value.GetType());
+            if (tools.ValueKind != JsonValueKind.Array || tools.EnumerateArray().Any(tool => tool.ValueKind != JsonValueKind.Object))
+            {
+                return false;
+            }
+
+            options.Tools.Clear();
+            foreach (JsonElement toolElement in tools.EnumerateArray())
+            {
+                options.Tools.Add(CreatePatchedTool(toolElement));
+            }
+
+            return true;
+        }
+
+        const string ToolsIndexPrefix = "$.tools[";
+        if (!key.StartsWith(ToolsIndexPrefix, StringComparison.Ordinal))
+        {
+            return false;
+        }
+
+        int closingBracket = key.IndexOf(']', ToolsIndexPrefix.Length);
+        if (closingBracket < 0 ||
+            !int.TryParse(key[ToolsIndexPrefix.Length..closingBracket], out int toolIndex) ||
+            toolIndex < 0)
+        {
+            return false;
+        }
+
+        string toolPath = key[(closingBracket + 1)..];
+        if (toolPath.Length > 0 && toolPath[0] is not ('.' or '['))
+        {
+            return false;
+        }
+
+        while (options.Tools.Count <= toolIndex)
+        {
+            options.Tools.Add(CreateEmptyPatchedTool());
+        }
+
+        if (toolPath.Length == 0)
+        {
+            if (value is null)
+            {
+                return false;
+            }
+
+            JsonElement tool = JsonSerializer.SerializeToElement(value, value.GetType());
+            if (tool.ValueKind != JsonValueKind.Object)
+            {
+                return false;
+            }
+
+            options.Tools[toolIndex] = CreatePatchedTool(tool);
+            return true;
+        }
+
+#pragma warning disable SCME0001 // System.ClientModel JsonPatch is for evaluation purposes only.
+        byte[] nestedPath = System.Text.Encoding.UTF8.GetBytes($"${toolPath}");
+        if (value is null)
+        {
+            options.Tools[toolIndex].Patch.SetNull(nestedPath);
+        }
+        else
+        {
+            options.Tools[toolIndex].Patch.Set(
+                nestedPath,
+                BinaryData.FromBytes(JsonSerializer.SerializeToUtf8Bytes(value, value.GetType())));
+        }
+#pragma warning restore SCME0001
+
+        return true;
+    }
+
+    private static ChatTool CreatePatchedTool(JsonElement toolElement)
+    {
+        ChatTool tool = CreateEmptyPatchedTool();
+
+#pragma warning disable SCME0001 // System.ClientModel JsonPatch is for evaluation purposes only.
+        foreach (JsonProperty property in toolElement.EnumerateObject())
+        {
+            string path = property.Name is "type" or "function"
+                ? $"$.{property.Name}"
+                : $"$[{JsonSerializer.Serialize(property.Name)}]";
+            byte[] propertyPath = System.Text.Encoding.UTF8.GetBytes(path);
+            if (property.Value.ValueKind == JsonValueKind.Null)
+            {
+                tool.Patch.SetNull(propertyPath);
+            }
+            else
+            {
+                tool.Patch.Set(propertyPath, BinaryData.FromBytes(JsonSerializer.SerializeToUtf8Bytes(property.Value)));
+            }
+        }
+#pragma warning restore SCME0001
+
+        return tool;
+    }
+
+    private static ChatTool CreateEmptyPatchedTool()
+    {
+        // ChatTool currently models function tools only. Use one as the SDK-owned carrier for the tools array,
+        // then remove its modeled defaults so ExtraBody remains the sole source of tool fields.
+        ChatTool tool = ChatTool.CreateFunctionTool("placeholder");
+
+#pragma warning disable SCME0001 // System.ClientModel JsonPatch is for evaluation purposes only.
+        tool.Patch.Remove(System.Text.Encoding.UTF8.GetBytes("$.type"));
+        tool.Patch.Remove(System.Text.Encoding.UTF8.GetBytes("$.function"));
+#pragma warning restore SCME0001
+
+        return tool;
+    }
+
     /// <summary>
     /// Applies all entries from <paramref name="settings"/>.<see cref="ExtraBody"/> to <paramref name="options"/>.
     /// </summary>