Improve Anthropic function calling

- factor out the common funciton calling logic form AnthropicChatModel to the AbstractToolCallSupport.
 - improve the AbstractToolCallSupport isToolCall to handle OpenAi and Anthropic.
 - fix an issue with the function calling streaming aggreagation leading to lost usage statistics.
 - small code improvements for OpenAiChatModel.

models/spring-ai-anthropic/src/main/java/org/springframework/ai/anthropic/AnthropicChatModel.java

@@ -15,40 +15,6 @@
  */
 package org.springframework.ai.anthropic;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.ai.anthropic.api.AnthropicApi;
-import org.springframework.ai.anthropic.api.AnthropicApi.AnthropicMessage;
-import org.springframework.ai.anthropic.api.AnthropicApi.ChatCompletionRequest;
-import org.springframework.ai.anthropic.api.AnthropicApi.ChatCompletionResponse;
-import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock;
-import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock.ContentBlockType;
-import org.springframework.ai.anthropic.api.AnthropicApi.Role;
-import org.springframework.ai.anthropic.metadata.AnthropicUsage;
-import org.springframework.ai.chat.messages.AssistantMessage;
-import org.springframework.ai.chat.messages.Message;
-import org.springframework.ai.chat.messages.MessageType;
-import org.springframework.ai.chat.messages.ToolResponseMessage;
-import org.springframework.ai.chat.messages.UserMessage;
-import org.springframework.ai.chat.metadata.ChatGenerationMetadata;
-import org.springframework.ai.chat.metadata.ChatResponseMetadata;
-import org.springframework.ai.chat.model.ChatModel;
-import org.springframework.ai.chat.model.ChatResponse;
-import org.springframework.ai.chat.model.Generation;
-import org.springframework.ai.chat.prompt.ChatOptions;
-import org.springframework.ai.chat.prompt.Prompt;
-import org.springframework.ai.model.ModelOptionsUtils;
-import org.springframework.ai.chat.model.AbstractToolCallSupport;
-import org.springframework.ai.model.function.FunctionCallbackContext;
-import org.springframework.ai.retry.RetryUtils;
-import org.springframework.http.ResponseEntity;
-import org.springframework.retry.support.RetryTemplate;
-import org.springframework.util.Assert;
-import org.springframework.util.CollectionUtils;
-import org.springframework.util.StringUtils;
-import reactor.core.publisher.Flux;
-import reactor.core.publisher.Mono;
-
 import java.util.ArrayList;
 import java.util.Base64;
 import java.util.HashSet;
@@ -57,6 +23,40 @@ import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.ai.anthropic.api.AnthropicApi;
+import org.springframework.ai.anthropic.api.AnthropicApi.AnthropicMessage;
+import org.springframework.ai.anthropic.api.AnthropicApi.ChatCompletionRequest;
+import org.springframework.ai.anthropic.api.AnthropicApi.ChatCompletionResponse;
+import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock;
+import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock.Type;
+import org.springframework.ai.anthropic.api.AnthropicApi.Role;
+import org.springframework.ai.anthropic.metadata.AnthropicUsage;
+import org.springframework.ai.chat.messages.AssistantMessage;
+import org.springframework.ai.chat.messages.MessageType;
+import org.springframework.ai.chat.messages.ToolResponseMessage;
+import org.springframework.ai.chat.messages.UserMessage;
+import org.springframework.ai.chat.metadata.ChatGenerationMetadata;
+import org.springframework.ai.chat.metadata.ChatResponseMetadata;
+import org.springframework.ai.chat.model.AbstractToolCallSupport;
+import org.springframework.ai.chat.model.ChatModel;
+import org.springframework.ai.chat.model.ChatResponse;
+import org.springframework.ai.chat.model.Generation;
+import org.springframework.ai.chat.prompt.ChatOptions;
+import org.springframework.ai.chat.prompt.Prompt;
+import org.springframework.ai.model.ModelOptionsUtils;
+import org.springframework.ai.model.function.FunctionCallbackContext;
+import org.springframework.ai.retry.RetryUtils;
+import org.springframework.http.ResponseEntity;
+import org.springframework.retry.support.RetryTemplate;
+import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.StringUtils;
+
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
 /**
  * The {@link ChatModel} implementation for the Anthropic service.
  *
@@ -150,17 +150,17 @@ public class AnthropicChatModel extends AbstractToolCallSupport implements ChatM
 
 		ChatCompletionRequest request = createRequest(prompt, false);
 
-		return this.retryTemplate.execute(ctx -> {
-			ResponseEntity<ChatCompletionResponse> completionEntity = this.anthropicApi.chatCompletionEntity(request);
+		ResponseEntity<ChatCompletionResponse> completionEntity = this.retryTemplate
+			.execute(ctx -> this.anthropicApi.chatCompletionEntity(request));
 
-			if (this.isToolFunctionCall(completionEntity.getBody())) {
-				List<Message> toolCallMessageConversation = this.handleToolCallRequests(prompt.getInstructions(),
-						completionEntity.getBody());
-				return this.call(new Prompt(toolCallMessageConversation, prompt.getOptions()));
-			}
+		ChatResponse chatResponse = toChatResponse(completionEntity.getBody());
 
-			return toChatResponse(completionEntity.getBody());
-		});
+		if (this.isToolCall(chatResponse, Set.of("tool_use"))) {
+			var toolCallConversation = handleToolCalls(prompt, chatResponse);
+			return this.call(new Prompt(toolCallConversation, prompt.getOptions()));
+		}
+
+		return chatResponse;
 	}
 
 	@Override
@@ -168,68 +168,66 @@ public class AnthropicChatModel extends AbstractToolCallSupport implements ChatM
 
 		ChatCompletionRequest request = createRequest(prompt, true);
 
-		return this.retryTemplate.execute(ctx -> {
+		Flux<ChatCompletionResponse> response = this.retryTemplate
+			.execute(ctx -> this.anthropicApi.chatCompletionStream(request));
 
-			Flux<ChatCompletionResponse> response = this.anthropicApi.chatCompletionStream(request);
+		return response.switchMap(chatCompletionResponse -> {
 
-			return response.switchMap(chatCompletionResponse -> {
+			ChatResponse chatResponse = toChatResponse(chatCompletionResponse);
 
-				if (this.isToolFunctionCall(chatCompletionResponse)) {
-					List<Message> toolCallMessageConversation = this.handleToolCallRequests(prompt.getInstructions(),
-							chatCompletionResponse);
-					return this.stream(new Prompt(toolCallMessageConversation, prompt.getOptions()));
-				}
+			if (this.isToolCall(chatResponse, Set.of("tool_use"))) {
+				var toolCallConversation = handleToolCalls(prompt, chatResponse);
+				return this.stream(new Prompt(toolCallConversation, prompt.getOptions()));
+			}
 
-				return Mono.just(chatCompletionResponse).map(this::toChatResponse);
-			});
+			return Mono.just(chatResponse);
 		});
 	}
 
-	private List<Message> handleToolCallRequests(List<Message> previousMessages,
-			ChatCompletionResponse chatCompletionResponse) {
-
-		AnthropicMessage anthropicAssistantMessage = new AnthropicMessage(chatCompletionResponse.content(),
-				Role.ASSISTANT);
-
-		List<ContentBlock> toolToUseList = anthropicAssistantMessage.content()
-			.stream()
-			.filter(c -> c.type() == ContentBlock.ContentBlockType.TOOL_USE)
-			.toList();
-
-		List<AssistantMessage.ToolCall> toolCalls = new ArrayList<>();
-
-		for (ContentBlock toolToUse : toolToUseList) {
-
-			var functionCallId = toolToUse.id();
-			var functionName = toolToUse.name();
-			var functionArguments = ModelOptionsUtils.toJsonString(toolToUse.input());
-
-			toolCalls.add(new AssistantMessage.ToolCall(functionCallId, "function", functionName, functionArguments));
-		}
-
-		AssistantMessage assistantMessage = new AssistantMessage("", Map.of(), toolCalls);
-		ToolResponseMessage toolResponseMessage = this.executeFunctions(assistantMessage);
-
-		// History
-		List<Message> toolCallMessageConversation = new ArrayList<>(previousMessages);
-		toolCallMessageConversation.add(assistantMessage);
-		toolCallMessageConversation.add(toolResponseMessage);
-
-		return toolCallMessageConversation;
-	}
-
 	private ChatResponse toChatResponse(ChatCompletionResponse chatCompletion) {
+
 		if (chatCompletion == null) {
 			logger.warn("Null chat completion returned");
 			return new ChatResponse(List.of());
 		}
 
-		List<Generation> generations = chatCompletion.content().stream().map(content -> {
-			return new Generation(content.text(), Map.of())
-				.withGenerationMetadata(ChatGenerationMetadata.from(chatCompletion.stopReason(), null));
-		}).toList();
+		List<Generation> generations = chatCompletion.content()
+			.stream()
+			.filter(content -> content.type() != ContentBlock.Type.TOOL_USE)
+			.map(content -> {
+				new AssistantMessage(content.text(), Map.of());
+				return new Generation(new AssistantMessage(content.text(), Map.of()),
+						ChatGenerationMetadata.from(chatCompletion.stopReason(), null));
+			})
+			.toList();
 
-		return new ChatResponse(generations, from(chatCompletion));
+		List<Generation> allGenerations = new ArrayList<>(generations);
+
+		List<ContentBlock> toolToUseList = chatCompletion.content()
+			.stream()
+			.filter(c -> c.type() == ContentBlock.Type.TOOL_USE)
+			.toList();
+
+		if (!CollectionUtils.isEmpty(toolToUseList)) {
+			List<AssistantMessage.ToolCall> toolCalls = new ArrayList<>();
+
+			for (ContentBlock toolToUse : toolToUseList) {
+
+				var functionCallId = toolToUse.id();
+				var functionName = toolToUse.name();
+				var functionArguments = ModelOptionsUtils.toJsonString(toolToUse.input());
+
+				toolCalls
+					.add(new AssistantMessage.ToolCall(functionCallId, "function", functionName, functionArguments));
+			}
+
+			AssistantMessage assistantMessage = new AssistantMessage("", Map.of(), toolCalls);
+			Generation toolCallGeneration = new Generation(assistantMessage,
+					ChatGenerationMetadata.from(chatCompletion.stopReason(), null));
+			allGenerations.add(toolCallGeneration);
+		}
+
+		return new ChatResponse(allGenerations, this.from(chatCompletion));
 	}
 
 	private ChatResponseMetadata from(AnthropicApi.ChatCompletionResponse result) {
@@ -288,8 +286,8 @@ public class AnthropicChatModel extends AbstractToolCallSupport implements ChatM
 					}
 					if (!CollectionUtils.isEmpty(assistantMessage.getToolCalls())) {
 						for (AssistantMessage.ToolCall toolCall : assistantMessage.getToolCalls()) {
-							contentBlocks.add(new ContentBlock(ContentBlockType.TOOL_USE, toolCall.id(),
-									toolCall.name(), ModelOptionsUtils.jsonToMap(toolCall.arguments())));
+							contentBlocks.add(new ContentBlock(Type.TOOL_USE, toolCall.id(), toolCall.name(),
+									ModelOptionsUtils.jsonToMap(toolCall.arguments())));
 						}
 					}
 					return new AnthropicMessage(contentBlocks, Role.ASSISTANT);
@@ -297,7 +295,7 @@ public class AnthropicChatModel extends AbstractToolCallSupport implements ChatM
 				else if (message.getMessageType() == MessageType.TOOL) {
 					List<ContentBlock> toolResponses = ((ToolResponseMessage) message).getResponses()
 						.stream()
-						.map(toolResponse -> new ContentBlock(ContentBlockType.TOOL_RESULT, toolResponse.id(),
+						.map(toolResponse -> new ContentBlock(Type.TOOL_RESULT, toolResponse.id(),
 								toolResponse.responseData()))
 						.toList();
 					return new AnthropicMessage(toolResponses, Role.USER);
@@ -355,16 +353,6 @@ public class AnthropicChatModel extends AbstractToolCallSupport implements ChatM
 		}).toList();
 	}
 
-	@SuppressWarnings("null")
-	protected boolean isToolFunctionCall(ChatCompletionResponse response) {
-		if (response == null || CollectionUtils.isEmpty(response.content())) {
-			return false;
-		}
-		return response.content()
-			.stream()
-			.anyMatch(content -> content.type() == ContentBlock.ContentBlockType.TOOL_USE);
-	}
-
 	@Override
 	public ChatOptions getDefaultOptions() {
 		return AnthropicChatOptions.fromOptions(this.defaultOptions);

models/spring-ai-anthropic/src/main/java/org/springframework/ai/anthropic/api/AnthropicApi.java

@@ -23,6 +23,8 @@ import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.ai.anthropic.api.StreamHelper.ChatCompletionResponseBuilder;
 import org.springframework.ai.model.ChatModelDescription;
 import org.springframework.ai.model.ModelOptionsUtils;
@@ -53,6 +55,8 @@ import reactor.core.publisher.Mono;
  */
 public class AnthropicApi {
 
+	private static final Logger logger = LoggerFactory.getLogger(AnthropicApi.class);
+
 	private static final String HEADER_X_API_KEY = "x-api-key";
 
 	private static final String HEADER_ANTHROPIC_VERSION = "anthropic-version";
@@ -415,7 +419,7 @@ public class AnthropicApi {
 	 */
 	@JsonInclude(Include.NON_NULL)
 	public record ContentBlock( // @formatter:off
-		@JsonProperty("type") ContentBlockType type,
+		@JsonProperty("type") Type type,
 		@JsonProperty("source") Source source,
 		@JsonProperty("text") String text,
 
@@ -438,67 +442,77 @@ public class AnthropicApi {
 		}
 
 		public ContentBlock(Source source) {
-			this(ContentBlockType.IMAGE, source, null, null, null, null, null, null, null);
+			this(Type.IMAGE, source, null, null, null, null, null, null, null);
 		}
 
 		public ContentBlock(String text) {
-			this(ContentBlockType.TEXT, null, text, null, null, null, null, null, null);
+			this(Type.TEXT, null, text, null, null, null, null, null, null);
 		}
 
 		// Tool result
-		public ContentBlock(ContentBlockType type, String toolUseId, String content) {
+		public ContentBlock(Type type, String toolUseId, String content) {
 			this(type, null, null, null, null, null, null, toolUseId, content);
 		}
 
-		public ContentBlock(ContentBlockType type, Source source, String text, Integer index) {
+		public ContentBlock(Type type, Source source, String text, Integer index) {
 			this(type, source, text, index, null, null, null, null, null);
 		}
 
 		// Tool use input JSON delta streaming
-		public ContentBlock(ContentBlockType type, String id, String name, Map<String, Object> input) {
+		public ContentBlock(Type type, String id, String name, Map<String, Object> input) {
 			this(type, null, null, null, id, name, input, null, null);
 		}
 
 		/**
-		 * The type of this message.
+		 * The ContentBlock type.
 		 */
-		public enum ContentBlockType {
+		public enum Type {
 
 			/**
 			 * Tool request
 			 */
 			@JsonProperty("tool_use")
-			TOOL_USE,
+			TOOL_USE("tool_use"),
 
 			/**
 			 * Send tool result back to LLM.
 			 */
 			@JsonProperty("tool_result")
-			TOOL_RESULT,
+			TOOL_RESULT("tool_result"),
 
 			/**
 			 * Text message.
 			 */
 			@JsonProperty("text")
-			TEXT,
+			TEXT("text"),
 
 			/**
 			 * Text delta message. Returned from the streaming response.
 			 */
 			@JsonProperty("text_delta")
-			TEXT_DELTA,
+			TEXT_DELTA("text_delta"),
 
 			/**
 			 * Tool use input partial JSON delta streaming.
 			 */
 			@JsonProperty("input_json_delta")
-			INPUT_JSON_DELTA,
+			INPUT_JSON_DELTA("input_json_delta"),
 
 			/**
 			 * Image message.
 			 */
 			@JsonProperty("image")
-			IMAGE;
+			IMAGE("image");
+
+			public final String value;
+
+			Type(String value) {
+				this.value = value;
+			}
+
+			public String getValue() {
+				return this.value;
+			}
 
 		}
 
@@ -902,6 +916,7 @@ public class AnthropicApi {
 			.takeUntil(SSE_DONE_PREDICATE)
 			.filter(SSE_DONE_PREDICATE.negate())
 			.map(content -> ModelOptionsUtils.jsonToObject(content, StreamEvent.class))
+			.filter(event -> event.type() != EventType.PING)
 			// Detect if the chunk is part of a streaming function call.
 			.map(event -> {
 				if (this.streamHelper.isToolUseStart(event)) {

models/spring-ai-anthropic/src/main/java/org/springframework/ai/anthropic/api/StreamHelper.java

@@ -21,7 +21,7 @@ import java.util.concurrent.atomic.AtomicReference;
 
 import org.springframework.ai.anthropic.api.AnthropicApi.ChatCompletionResponse;
 import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock;
-import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock.ContentBlockType;
+import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock.Type;
 import org.springframework.ai.anthropic.api.AnthropicApi.Role;
 import org.springframework.ai.anthropic.api.AnthropicApi.Usage;
 import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlockDeltaEvent;
@@ -55,15 +55,15 @@ public class StreamHelper {
 		if (event == null || event.type() == null || event.type() != EventType.CONTENT_BLOCK_START) {
 			return false;
 		}
-		return "tool_use".equals(((ContentBlockStartEvent) event).contentBlock().type());
+		return ContentBlock.Type.TOOL_USE.getValue().equals(((ContentBlockStartEvent) event).contentBlock().type());
 	}
 
 	public boolean isToolUseFinish(StreamEvent event) {
 
-		if (event == null || event.type() == null || event.type() != EventType.MESSAGE_DELTA) {
+		if (event == null || event.type() == null || event.type() != EventType.CONTENT_BLOCK_STOP) {
 			return false;
 		}
-		return "tool_use".equals(((MessageDeltaEvent) event).delta().stopReason());
+		return true;
 	}
 
 	public StreamEvent mergeToolUseEvents(StreamEvent previousEvent, StreamEvent event) {
@@ -73,7 +73,7 @@ public class StreamHelper {
 		if (event.type() == EventType.CONTENT_BLOCK_START) {
 			ContentBlockStartEvent contentBlockStart = (ContentBlockStartEvent) event;
 
-			if ("tool_use".equals(contentBlockStart.contentBlock().type())) {
+			if (ContentBlock.Type.TOOL_USE.getValue().equals(contentBlockStart.contentBlock().type())) {
 				ContentBlockStartEvent.ContentBlockToolUse cbToolUse = (ContentBlockToolUse) contentBlockStart
 					.contentBlock();
 
@@ -85,7 +85,7 @@ public class StreamHelper {
 		}
 		else if (event.type() == EventType.CONTENT_BLOCK_DELTA) {
 			ContentBlockDeltaEvent contentBolckDelta = (ContentBlockDeltaEvent) event;
-			if ("input_json_delta".equals(contentBolckDelta.delta().type())) {
+			if (ContentBlock.Type.INPUT_JSON_DELTA.getValue().equals(contentBolckDelta.delta().type())) {
 				return eventAggregator
 					.appendPartialJson(((ContentBlockDeltaJson) contentBolckDelta.delta()).partialJson());
 			}
@@ -96,9 +96,6 @@ public class StreamHelper {
 				return eventAggregator;
 			}
 		}
-		else if (isToolUseFinish(event)) {
-			return eventAggregator;
-		}
 
 		return event;
 	}
@@ -128,8 +125,7 @@ public class StreamHelper {
 
 				List<ContentBlock> content = eventToolUseBuilder.getToolContentBlocks()
 					.stream()
-					.map(tooToUse -> new ContentBlock(ContentBlockType.TOOL_USE, tooToUse.id(), tooToUse.name(),
-							tooToUse.input()))
+					.map(tooToUse -> new ContentBlock(Type.TOOL_USE, tooToUse.id(), tooToUse.name(), tooToUse.input()))
 					.toList();
 				contentBlockReference.get().withContent(content);
 			}
@@ -142,7 +138,7 @@ public class StreamHelper {
 							+ contentBlockStartEvent.contentBlock().type());
 
 			ContentBlockText contentBlockText = (ContentBlockText) contentBlockStartEvent.contentBlock();
-			ContentBlock contentBlock = new ContentBlock(ContentBlockType.TEXT, null, contentBlockText.text(),
+			ContentBlock contentBlock = new ContentBlock(Type.TEXT, null, contentBlockText.text(),
 					contentBlockStartEvent.index());
 			contentBlockReference.get().withType(event.type().name()).withContent(List.of(contentBlock));
 		}
@@ -156,8 +152,7 @@ public class StreamHelper {
 
 			ContentBlockDeltaText deltaTxt = (ContentBlockDeltaText) contentBlockDeltaEvent.delta();
 
-			var contentBlock = new ContentBlock(ContentBlockType.TEXT_DELTA, null, deltaTxt.text(),
-					contentBlockDeltaEvent.index());
+			var contentBlock = new ContentBlock(Type.TEXT_DELTA, null, deltaTxt.text(), contentBlockDeltaEvent.index());
 
 			contentBlockReference.get().withType(event.type().name()).withContent(List.of(contentBlock));
 		}
@@ -182,7 +177,6 @@ public class StreamHelper {
 			}
 		}
 		else if (event.type().equals(EventType.MESSAGE_STOP)) {
-
 		}
 		else {
 			contentBlockReference.get().withType(event.type().name()).withContent(List.of());

models/spring-ai-anthropic/src/test/java/org/springframework/ai/anthropic/api/tool/AnthropicApiToolIT.java

@@ -29,7 +29,7 @@ import org.springframework.ai.anthropic.api.AnthropicApi;
 import org.springframework.ai.anthropic.api.AnthropicApi.ChatCompletionResponse;
 import org.springframework.ai.anthropic.api.AnthropicApi.ChatCompletionRequest;
 import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock;
-import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock.ContentBlockType;
+import org.springframework.ai.anthropic.api.AnthropicApi.ContentBlock.Type;
 import org.springframework.ai.anthropic.api.AnthropicApi.AnthropicMessage;
 import org.springframework.ai.anthropic.api.AnthropicApi.Role;
 import org.springframework.ai.anthropic.api.AnthropicApi.Tool;
@@ -117,7 +117,7 @@ public class AnthropicApiToolIT {
 		List<ContentBlock> toolToUseList = response.getBody()
 			.content()
 			.stream()
-			.filter(c -> c.type() == ContentBlock.ContentBlockType.TOOL_USE)
+			.filter(c -> c.type() == ContentBlock.Type.TOOL_USE)
 			.toList();
 
 		if (CollectionUtils.isEmpty(toolToUseList)) {
@@ -146,7 +146,7 @@ public class AnthropicApiToolIT {
 
 			logger.info("Function response : " + content);
 
-			toolResults.add(new ContentBlock(ContentBlockType.TOOL_RESULT, id, content));
+			toolResults.add(new ContentBlock(Type.TOOL_RESULT, id, content));
 		}
 
 		// Add function response message to the conversation history

models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatModel.java

@@ -186,18 +186,6 @@ public class OpenAiChatModel extends AbstractToolCallSupport implements ChatMode
 		return chatResponse;
 	}
 
-	public static ChatResponseMetadata from(OpenAiApi.ChatCompletion result, RateLimit rateLimit) {
-		Assert.notNull(result, "OpenAI ChatCompletionResult must not be null");
-		return ChatResponseMetadata.builder()
-			.withId(result.id())
-			.withUsage(OpenAiUsage.from(result.usage()))
-			.withModel(result.model())
-			.withRateLimit(rateLimit)
-			.withKeyValue("created", result.created())
-			.withKeyValue("system-fingerprint", result.systemFingerprint())
-			.build();
-	}
-
 	@Override
 	public Flux<ChatResponse> stream(Prompt prompt) {
 
@@ -232,7 +220,7 @@ public class OpenAiChatModel extends AbstractToolCallSupport implements ChatMode
 					// @formatter:on
 
 					if (chatCompletion2.usage() != null) {
-						return new ChatResponse(generations, from(chatCompletion2));
+						return new ChatResponse(generations, from(chatCompletion2, null));
 					}
 					else {
 						return new ChatResponse(generations);
@@ -259,18 +247,7 @@ public class OpenAiChatModel extends AbstractToolCallSupport implements ChatMode
 		});
 	}
 
-	private ChatResponseMetadata from(OpenAiApi.ChatCompletion result) {
-		Assert.notNull(result, "OpenAI ChatCompletionResult must not be null");
-		return ChatResponseMetadata.builder()
-			.withId(result.id())
-			.withUsage(OpenAiUsage.from(result.usage()))
-			.withModel(result.model())
-			.withKeyValue("created", result.created())
-			.withKeyValue("system-fingerprint", result.systemFingerprint())
-			.build();
-	}
-
-	private static Generation buildGeneration(Choice choice, Map<String, Object> metadata) {
+	private Generation buildGeneration(Choice choice, Map<String, Object> metadata) {
 		List<AssistantMessage.ToolCall> toolCalls = choice.message().toolCalls() == null ? List.of()
 				: choice.message()
 					.toolCalls()
@@ -285,6 +262,21 @@ public class OpenAiChatModel extends AbstractToolCallSupport implements ChatMode
 		return new Generation(assistantMessage, generationMetadata);
 	}
 
+	private ChatResponseMetadata from(OpenAiApi.ChatCompletion result, RateLimit rateLimit) {
+		Assert.notNull(result, "OpenAI ChatCompletionResult must not be null");
+		var builder = ChatResponseMetadata.builder()
+			.withId(result.id())
+			.withUsage(OpenAiUsage.from(result.usage()))
+			.withModel(result.model())
+			.withRateLimit(rateLimit)
+			.withKeyValue("created", result.created())
+			.withKeyValue("system-fingerprint", result.systemFingerprint());
+		if (rateLimit != null) {
+			builder.withRateLimit(rateLimit);
+		}
+		return builder.build();
+	}
+
 	/**
 	 * Convert the ChatCompletionChunk into a ChatCompletion. The Usage is set to null.
 	 * @param chunk the ChatCompletionChunk to convert

spring-ai-core/src/main/java/org/springframework/ai/chat/messages/AssistantMessage.java

@@ -77,4 +77,10 @@ public class AssistantMessage extends AbstractMessage {
 		return Objects.hash(super.hashCode(), toolCalls);
 	}
 
+	@Override
+	public String toString() {
+		return "AssistantMessage [messageType=" + messageType + ", toolCalls=" + toolCalls + ", textContent="
+				+ textContent + ", metadata=" + metadata + "]";
+	}
+
 }

spring-ai-core/src/main/java/org/springframework/ai/chat/metadata/ChatGenerationMetadata.java

@@ -51,6 +51,12 @@ public interface ChatGenerationMetadata extends ResultMetadata {
 			public String getFinishReason() {
 				return finishReason;
 			}
+
+			@Override
+			public String toString() {
+				return "ChatGenerationMetadata{finishReason=" + finishReason + "," + "contentFilterMetadata="
+						+ contentFilterMetadata + "}";
+			}
 		};
 	}
 

spring-ai-core/src/main/java/org/springframework/ai/chat/model/AbstractToolCallSupport.java

@@ -19,6 +19,7 @@ import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -98,7 +99,14 @@ public abstract class AbstractToolCallSupport {
 	}
 
 	protected List<Message> handleToolCalls(Prompt prompt, ChatResponse response) {
-		AssistantMessage assistantMessage = response.getResult().getOutput();
+		Optional<Generation> toolCallGeneration = response.getResults()
+			.stream()
+			.filter(g -> !CollectionUtils.isEmpty(g.getOutput().getToolCalls()))
+			.findFirst();
+		if (toolCallGeneration.isEmpty()) {
+			throw new IllegalStateException("No tool call generation found in the response!");
+		}
+		AssistantMessage assistantMessage = toolCallGeneration.get().getOutput();
 		ToolResponseMessage toolMessageResponse = this.executeFunctions(assistantMessage);
 		return this.buildToolCallConversation(prompt.getInstructions(), assistantMessage, toolMessageResponse);
 	}
@@ -180,11 +188,16 @@ public abstract class AbstractToolCallSupport {
 			return false;
 		}
 
-		var generation = generations.get(0);
+		return generations.stream().anyMatch(g -> isToolCall(g, toolCallFinishReasons));
+	}
+
+	protected boolean isToolCall(Generation generation, Set<String> toolCallFinishReasons) {
+		var finishReason = (generation.getMetadata().getFinishReason() != null)
+				? generation.getMetadata().getFinishReason() : "";
 		return !CollectionUtils.isEmpty(generation.getOutput().getToolCalls()) && toolCallFinishReasons.stream()
 			.map(s -> s.toLowerCase())
 			.toList()
-			.contains(generation.getMetadata().getFinishReason().toLowerCase());
+			.contains(finishReason.toLowerCase());
 	}
 
 }