diff --git a/spring-ai-model/src/main/java/org/springframework/ai/chat/model/MessageAggregator.java b/spring-ai-model/src/main/java/org/springframework/ai/chat/model/MessageAggregator.java
index 839d99e23d8..222d53d426f 100644
--- a/spring-ai-model/src/main/java/org/springframework/ai/chat/model/MessageAggregator.java
+++ b/spring-ai-model/src/main/java/org/springframework/ai/chat/model/MessageAggregator.java
@@ -16,6 +16,7 @@
 
 package org.springframework.ai.chat.model;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -24,6 +25,7 @@
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.util.CollectionUtils;
 import reactor.core.publisher.Flux;
 
 import org.springframework.ai.chat.messages.AssistantMessage;
@@ -35,6 +37,8 @@
 import org.springframework.ai.chat.metadata.Usage;
 import org.springframework.util.StringUtils;
 
+import static org.springframework.ai.chat.messages.AssistantMessage.*;
+
 /**
  * Helper that for streaming chat responses, aggregate the chat response messages into a
  * single AssistantMessage. Job is performed in parallel to the chat response processing.
@@ -42,6 +46,7 @@
  * @author Christian Tzolov
  * @author Alexandros Pappas
  * @author Thomas Vitale
+ * @author Heonwoo Kim
  * @since 1.0.0
  */
 public class MessageAggregator {
@@ -54,6 +59,7 @@ public Flux<ChatResponse> aggregate(Flux<ChatResponse> fluxChatResponse,
 		// Assistant Message
 		AtomicReference<StringBuilder> messageTextContentRef = new AtomicReference<>(new StringBuilder());
 		AtomicReference<Map<String, Object>> messageMetadataMapRef = new AtomicReference<>();
+		AtomicReference<List<ToolCall>> toolCallsRef = new AtomicReference<>(new ArrayList<>());
 
 		// ChatGeneration Metadata
 		AtomicReference<ChatGenerationMetadata> generationMetadataRef = new AtomicReference<>(
@@ -73,6 +79,7 @@ public Flux<ChatResponse> aggregate(Flux<ChatResponse> fluxChatResponse,
 		return fluxChatResponse.doOnSubscribe(subscription -> {
 			messageTextContentRef.set(new StringBuilder());
 			messageMetadataMapRef.set(new HashMap<>());
+			toolCallsRef.set(new ArrayList<>());
 			metadataIdRef.set("");
 			metadataModelRef.set("");
 			metadataUsagePromptTokensRef.set(0);
@@ -94,6 +101,11 @@ public Flux<ChatResponse> aggregate(Flux<ChatResponse> fluxChatResponse,
 				if (chatResponse.getResult().getOutput().getMetadata() != null) {
 					messageMetadataMapRef.get().putAll(chatResponse.getResult().getOutput().getMetadata());
 				}
+				AssistantMessage outputMessage = chatResponse.getResult().getOutput();
+				if (!CollectionUtils.isEmpty(outputMessage.getToolCalls())) {
+					toolCallsRef.get().addAll(outputMessage.getToolCalls());
+				}
+
 			}
 			if (chatResponse.getMetadata() != null) {
 				if (chatResponse.getMetadata().getUsage() != null) {
@@ -119,6 +131,13 @@ public Flux<ChatResponse> aggregate(Flux<ChatResponse> fluxChatResponse,
 				if (StringUtils.hasText(chatResponse.getMetadata().getModel())) {
 					metadataModelRef.set(chatResponse.getMetadata().getModel());
 				}
+				Object toolCallsFromMetadata = chatResponse.getMetadata().get("toolCalls");
+				if (toolCallsFromMetadata instanceof List) {
+					@SuppressWarnings("unchecked")
+					List<ToolCall> toolCallsList = (List<ToolCall>) toolCallsFromMetadata;
+					toolCallsRef.get().addAll(toolCallsList);
+				}
+
 			}
 		}).doOnComplete(() -> {
 
@@ -133,12 +152,25 @@ public Flux<ChatResponse> aggregate(Flux<ChatResponse> fluxChatResponse,
 				.promptMetadata(metadataPromptMetadataRef.get())
 				.build();
 
-			onAggregationComplete.accept(new ChatResponse(List.of(new Generation(
-					new AssistantMessage(messageTextContentRef.get().toString(), messageMetadataMapRef.get()),
+			AssistantMessage finalAssistantMessage;
+			List<ToolCall> collectedToolCalls = toolCallsRef.get();
+
+			if (!CollectionUtils.isEmpty(collectedToolCalls)) {
+
+				finalAssistantMessage = new AssistantMessage(messageTextContentRef.get().toString(),
+						messageMetadataMapRef.get(), collectedToolCalls);
+			}
+			else {
+				finalAssistantMessage = new AssistantMessage(messageTextContentRef.get().toString(),
+						messageMetadataMapRef.get());
+			}
+			onAggregationComplete.accept(new ChatResponse(List.of(new Generation(finalAssistantMessage,
+
 					generationMetadataRef.get())), chatResponseMetadata));
 
 			messageTextContentRef.set(new StringBuilder());
 			messageMetadataMapRef.set(new HashMap<>());
+			toolCallsRef.set(new ArrayList<>());
 			metadataIdRef.set("");
 			metadataModelRef.set("");
 			metadataUsagePromptTokensRef.set(0);
diff --git a/spring-ai-model/src/test/java/org/springframework/ai/chat/model/ChatResponseTests.java b/spring-ai-model/src/test/java/org/springframework/ai/chat/model/ChatResponseTests.java
index a9d673e23be..08cdc993fba 100644
--- a/spring-ai-model/src/test/java/org/springframework/ai/chat/model/ChatResponseTests.java
+++ b/spring-ai-model/src/test/java/org/springframework/ai/chat/model/ChatResponseTests.java
@@ -19,27 +19,32 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.junit.jupiter.api.Test;
 
 import org.springframework.ai.chat.messages.AssistantMessage;
 import org.springframework.ai.chat.metadata.ChatGenerationMetadata;
+import org.springframework.ai.chat.metadata.ChatResponseMetadata;
+import reactor.core.publisher.Flux;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.springframework.ai.chat.messages.AssistantMessage.*;
 
 /**
  * Unit tests for {@link ChatResponse}.
  *
  * @author Thomas Vitale
+ * @author Heonwoo Kim
  */
 class ChatResponseTests {
 
 	@Test
 	void whenToolCallsArePresentThenReturnTrue() {
 		ChatResponse chatResponse = ChatResponse.builder()
-			.generations(List.of(new Generation(new AssistantMessage("", Map.of(),
-					List.of(new AssistantMessage.ToolCall("toolA", "function", "toolA", "{}"))))))
+			.generations(List.of(new Generation(
+					new AssistantMessage("", Map.of(), List.of(new ToolCall("toolA", "function", "toolA", "{}"))))))
 			.build();
 		assertThat(chatResponse.hasToolCalls()).isTrue();
 	}
@@ -80,4 +85,45 @@ void whenFinishReasonIsNotPresent() {
 		assertThat(chatResponse.hasFinishReasons(Set.of("completed"))).isFalse();
 	}
 
+	@Test
+	void messageAggregatorShouldCorrectlyAggregateToolCallsFromStream() {
+
+		MessageAggregator aggregator = new MessageAggregator();
+
+		ChatResponse chunk1 = new ChatResponse(
+				List.of(new Generation(new AssistantMessage("Thinking about the weather... "))));
+
+		ToolCall weatherToolCall = new ToolCall("tool-id-123", "function", "getCurrentWeather",
+				"{\"location\": \"Seoul\"}");
+
+		Map<String, Object> metadataWithToolCall = Map.of("toolCalls", List.of(weatherToolCall));
+		ChatResponseMetadata responseMetadataForChunk2 = ChatResponseMetadata.builder()
+			.metadata(metadataWithToolCall)
+			.build();
+
+		ChatResponse chunk2 = new ChatResponse(List.of(new Generation(new AssistantMessage(""))),
+				responseMetadataForChunk2);
+
+		Flux<ChatResponse> streamingResponse = Flux.just(chunk1, chunk2);
+
+		AtomicReference<ChatResponse> aggregatedResponseRef = new AtomicReference<>();
+
+		aggregator.aggregate(streamingResponse, aggregatedResponseRef::set).blockLast();
+
+		ChatResponse finalResponse = aggregatedResponseRef.get();
+		assertThat(finalResponse).isNotNull();
+
+		AssistantMessage finalAssistantMessage = finalResponse.getResult().getOutput();
+
+		assertThat(finalAssistantMessage).isNotNull();
+		assertThat(finalAssistantMessage.getText()).isEqualTo("Thinking about the weather... ");
+		assertThat(finalAssistantMessage.hasToolCalls()).isTrue();
+		assertThat(finalAssistantMessage.getToolCalls()).hasSize(1);
+
+		ToolCall resultToolCall = finalAssistantMessage.getToolCalls().get(0);
+		assertThat(resultToolCall.id()).isEqualTo("tool-id-123");
+		assertThat(resultToolCall.name()).isEqualTo("getCurrentWeather");
+		assertThat(resultToolCall.arguments()).isEqualTo("{\"location\": \"Seoul\"}");
+	}
+
 }