fix: Fixed the issue where the returnDirect attribute was not effective on the MCP server side.

mcp/common/src/main/java/org/springframework/ai/mcp/AsyncMcpToolCallback.java

@@ -19,6 +19,7 @@
 import java.util.Map;
 
 import io.modelcontextprotocol.client.McpAsyncClient;
+import io.modelcontextprotocol.spec.McpSchema;
 import io.modelcontextprotocol.spec.McpSchema.CallToolRequest;
 import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
 import io.modelcontextprotocol.spec.McpSchema.Tool;
@@ -33,6 +34,7 @@
 import org.springframework.ai.tool.definition.DefaultToolDefinition;
 import org.springframework.ai.tool.definition.ToolDefinition;
 import org.springframework.ai.tool.execution.ToolExecutionException;
+import org.springframework.ai.tool.metadata.ToolMetadata;
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
@@ -45,15 +47,20 @@
  *
  * @author Christian Tzolov
  * @author YunKui Lu
+ * @author Sun Yuhan
  */
 public class AsyncMcpToolCallback implements ToolCallback {
 
 	private static final Logger logger = LoggerFactory.getLogger(AsyncMcpToolCallback.class);
 
+	private static final ToolMetadata DEFAULT_TOOL_METADATA = ToolMetadata.builder().build();
+
 	private final McpAsyncClient mcpClient;
 
 	private final Tool tool;
 
+	private final ToolMetadata toolMetadata;
+
 	private final String prefixedToolName;
 
 	private final ToolContextToMcpMetaConverter toolContextToMcpMetaConverter;
@@ -88,6 +95,14 @@ private AsyncMcpToolCallback(McpAsyncClient mcpClient, Tool tool, String prefixe
 		this.tool = tool;
 		this.prefixedToolName = prefixedToolName;
 		this.toolContextToMcpMetaConverter = toolContextToMcpMetaConverter;
+		McpSchema.ToolAnnotations annotations = tool.annotations();
+		Boolean returnDirect = (annotations != null) ? annotations.returnDirect() : null;
+		if (returnDirect != null) {
+			this.toolMetadata = ToolMetadata.builder().returnDirect(returnDirect).build();
+		}
+		else {
+			this.toolMetadata = DEFAULT_TOOL_METADATA;
+		}
 	}
 
 	@Override
@@ -149,6 +164,11 @@ public String call(String toolCallInput, @Nullable ToolContext toolContext) {
 		return ModelOptionsUtils.toJsonString(response.content());
 	}
 
+	@Override
+	public ToolMetadata getToolMetadata() {
+		return this.toolMetadata;
+	}
+
 	/**
 	 * Creates a builder for constructing AsyncMcpToolCallback instances.
 	 * @return a new builder

mcp/common/src/main/java/org/springframework/ai/mcp/McpToolUtils.java

@@ -40,6 +40,7 @@
 import org.springframework.ai.chat.model.ToolContext;
 import org.springframework.ai.model.ModelOptionsUtils;
 import org.springframework.ai.tool.ToolCallback;
+import org.springframework.ai.tool.metadata.ToolMetadata;
 import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeType;
@@ -63,6 +64,7 @@
  * </ul>
  *
  * @author Christian Tzolov
+ * @author Sun Yuhan
  */
 public final class McpToolUtils {
 
@@ -228,12 +230,18 @@ public static McpStatelessServerFeatures.SyncToolSpecification toStatelessSyncTo
 
 	private static SharedSyncToolSpecification toSharedSyncToolSpecification(ToolCallback toolCallback,
 			MimeType mimeType) {
+		boolean returnDirect = Optional.ofNullable(toolCallback.getToolMetadata())
+			.map(ToolMetadata::returnDirect)
+			.orElse(false);
+		McpSchema.ToolAnnotations toolAnnotations = new McpSchema.ToolAnnotations(null, null, null, null, null,
+				returnDirect);
 
 		var tool = McpSchema.Tool.builder()
 			.name(toolCallback.getToolDefinition().name())
 			.description(toolCallback.getToolDefinition().description())
 			.inputSchema(ModelOptionsUtils.jsonToObject(toolCallback.getToolDefinition().inputSchema(),
 					McpSchema.JsonSchema.class))
+			.annotations(toolAnnotations)
 			.build();
 
 		return new SharedSyncToolSpecification(tool, (exchangeOrContext, request) -> {

mcp/common/src/main/java/org/springframework/ai/mcp/SyncMcpToolCallback.java

@@ -19,6 +19,7 @@
 import java.util.Map;
 
 import io.modelcontextprotocol.client.McpSyncClient;
+import io.modelcontextprotocol.spec.McpSchema;
 import io.modelcontextprotocol.spec.McpSchema.CallToolRequest;
 import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
 import io.modelcontextprotocol.spec.McpSchema.Tool;
@@ -32,6 +33,7 @@
 import org.springframework.ai.tool.definition.DefaultToolDefinition;
 import org.springframework.ai.tool.definition.ToolDefinition;
 import org.springframework.ai.tool.execution.ToolExecutionException;
+import org.springframework.ai.tool.metadata.ToolMetadata;
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
@@ -41,16 +43,21 @@
  *
  * @author Christian Tzolov
  * @author YunKui Lu
+ * @author Sun Yuhan
  * @since 1.0.0
  */
 public class SyncMcpToolCallback implements ToolCallback {
 
 	private static final Logger logger = LoggerFactory.getLogger(SyncMcpToolCallback.class);
 
+	private static final ToolMetadata DEFAULT_TOOL_METADATA = ToolMetadata.builder().build();
+
 	private final McpSyncClient mcpClient;
 
 	private final Tool tool;
 
+	private final ToolMetadata toolMetadata;
+
 	private final String prefixedToolName;
 
 	private final ToolContextToMcpMetaConverter toolContextToMcpMetaConverter;
@@ -85,6 +92,14 @@ private SyncMcpToolCallback(McpSyncClient mcpClient, Tool tool, String prefixedT
 		this.tool = tool;
 		this.prefixedToolName = prefixedToolName;
 		this.toolContextToMcpMetaConverter = toolContextToMcpMetaConverter;
+		McpSchema.ToolAnnotations annotations = tool.annotations();
+		Boolean returnDirect = (annotations != null) ? annotations.returnDirect() : null;
+		if (returnDirect != null) {
+			this.toolMetadata = ToolMetadata.builder().returnDirect(returnDirect).build();
+		}
+		else {
+			this.toolMetadata = DEFAULT_TOOL_METADATA;
+		}
 	}
 
 	@Override
@@ -149,6 +164,11 @@ public String call(String toolCallInput, @Nullable ToolContext toolContext) {
 		return ModelOptionsUtils.toJsonString(response.content());
 	}
 
+	@Override
+	public ToolMetadata getToolMetadata() {
+		return this.toolMetadata;
+	}
+
 	/**
 	 * Creates a builder for constructing {@code SyncMcpToolCallback} instances.
 	 * @return a new builder

mcp/common/src/test/java/org/springframework/ai/mcp/AsyncMcpToolCallbackTest.java

@@ -204,6 +204,8 @@ void getToolDefinitionShouldReturnCorrectDefinition() {
 		when(this.tool.description()).thenReturn("Test tool description");
 		var jsonSchema = mock(McpSchema.JsonSchema.class);
 		when(this.tool.inputSchema()).thenReturn(jsonSchema);
+		var toolAnnotations = new McpSchema.ToolAnnotations(null, false, false, false, false, true);
+		when(this.tool.annotations()).thenReturn(toolAnnotations);
 
 		// Act
 		var callback = AsyncMcpToolCallback.builder()
@@ -213,11 +215,13 @@ void getToolDefinitionShouldReturnCorrectDefinition() {
 			.build();
 
 		ToolDefinition definition = callback.getToolDefinition();
+		var toolMetadata = callback.getToolMetadata();
 
 		// Assert
 		assertThat(definition.name()).isEqualTo("prefix_testTool");
 		assertThat(definition.description()).isEqualTo("Test tool description");
 		assertThat(definition.inputSchema()).isNotNull();
+		assertThat(toolMetadata.returnDirect()).isEqualTo(true);
 	}
 
 	@Test

mcp/common/src/test/java/org/springframework/ai/mcp/SyncMcpToolCallbackTests.java

@@ -51,6 +51,7 @@ class SyncMcpToolCallbackTests {
 	@Test
 	void getToolDefinitionShouldReturnCorrectDefinition() {
 		var clientInfo = new Implementation("testClient", "1.0.0");
+
 		when(this.tool.name()).thenReturn("testTool");
 		when(this.tool.description()).thenReturn("Test tool description");
 

mcp/common/src/test/java/org/springframework/ai/mcp/ToolUtilsTests.java

@@ -37,6 +37,7 @@
 import org.springframework.ai.tool.ToolCallback;
 import org.springframework.ai.tool.definition.DefaultToolDefinition;
 import org.springframework.ai.tool.definition.ToolDefinition;
+import org.springframework.ai.tool.metadata.ToolMetadata;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
@@ -314,8 +315,10 @@ private ToolCallback createMockToolCallback(String name, String result) {
 			.description("Test tool")
 			.inputSchema("{}")
 			.build();
+		ToolMetadata metadata = ToolMetadata.builder().build();
 		when(callback.getToolDefinition()).thenReturn(definition);
 		when(callback.call(anyString(), any())).thenReturn(result);
+		when(callback.getToolMetadata()).thenReturn(metadata);
 		return callback;
 	}
 
@@ -326,8 +329,10 @@ private ToolCallback createMockToolCallback(String name, RuntimeException error)
 			.description("Test tool")
 			.inputSchema("{}")
 			.build();
+		ToolMetadata metadata = ToolMetadata.builder().build();
 		when(callback.getToolDefinition()).thenReturn(definition);
 		when(callback.call(anyString(), any())).thenThrow(error);
+		when(callback.getToolMetadata()).thenReturn(metadata);
 		return callback;
 	}