diff --git a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java
index 5bc83eade..605697906 100644
--- a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java
+++ b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java
@@ -319,7 +319,7 @@ public class OpenAiApi {
 			@JsonProperty("temperature") Float temperature,
 			@JsonProperty("top_p") Float topP,
 			@JsonProperty("tools") List<FunctionTool> tools,
-			@JsonProperty("tool_choice") String toolChoice,
+			@JsonProperty("tool_choice") Object toolChoice,
 			@JsonProperty("user") String user) {
 
 		/**
@@ -360,7 +360,7 @@ public class OpenAiApi {
 		 * @param toolChoice Controls which (if any) function is called by the model.
 		 */
 		public ChatCompletionRequest(List<ChatCompletionMessage> messages, String model,
-				List<FunctionTool> tools, String toolChoice) {
+				List<FunctionTool> tools, Object toolChoice) {
 			this(messages, model, null, null, null, null, null, null, null,
 					null, null, null, false, 0.8f, null,
 					tools, toolChoice, null);
@@ -396,8 +396,8 @@ public class OpenAiApi {
 			/**
 			 * Specifying a particular function forces the model to call that function.
 			 */
-			public static String FUNCTION(String functionName) {
-				return ModelOptionsUtils.toJsonString(Map.of("type", "function", "function", Map.of("name", functionName)));
+			public static Object FUNCTION(String functionName) {
+				return Map.of("type", "function", "function", Map.of("name", functionName));
 			}
 		}
 
diff --git a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java
index 4138a24a9..c13f7196f 100644
--- a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java
+++ b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java
@@ -32,6 +32,7 @@ import org.springframework.ai.openai.api.OpenAiApi.ChatCompletion;
 import org.springframework.ai.openai.api.OpenAiApi.ChatCompletionMessage;
 import org.springframework.ai.openai.api.OpenAiApi.ChatCompletionMessage.Role;
 import org.springframework.ai.openai.api.OpenAiApi.ChatCompletionMessage.ToolCall;
+import org.springframework.ai.openai.api.OpenAiApi.ChatCompletionRequest.ToolChoiceBuilder;
 import org.springframework.ai.openai.api.OpenAiApi.ChatCompletionRequest;
 import org.springframework.ai.openai.api.OpenAiApi.FunctionTool.Type;
 import org.springframework.http.ResponseEntity;
@@ -89,19 +90,11 @@ public class OpenAiApiToolFunctionCallIT {
 								}
 								""")));
 
-		// Or you can use the
-		// ModelOptionsUtils.getJsonSchema(FakeWeatherService.Request.class))) to
-		// auto-generate the JSON schema like:
-		// var functionTool = new OpenAiApi.FunctionTool(Type.FUNCTION, new
-		// OpenAiApi.FunctionTool.Function(
-		// "Get the weather in location. Return temperature in 30°F or 30°C format.",
-		// "getCurrentWeather",
-		// ModelOptionsUtils.getJsonSchema(FakeWeatherService.Request.class)));
-
 		List<ChatCompletionMessage> messages = new ArrayList<>(List.of(message));
 
 		ChatCompletionRequest chatCompletionRequest = new ChatCompletionRequest(messages, "gpt-4-turbo-preview",
-				List.of(functionTool), null);
+				List.of(functionTool), ToolChoiceBuilder.AUTO);
+		// List.of(functionTool), ToolChoiceBuilder.FUNCTION("getCurrentWeather"));
 
 		ResponseEntity<ChatCompletion> chatCompletion = completionApi.chatCompletionEntity(chatCompletionRequest);