fix: Improved compatibility with empty ToolMetadata and enhanced some unit tests.

Signed-off-by: Sun Yuhan <[email protected]>

Author: sunyuhan1998

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

@@ -30,6 +30,7 @@
 import io.modelcontextprotocol.server.McpSyncServerExchange;
 import io.modelcontextprotocol.spec.McpSchema;
 import io.modelcontextprotocol.spec.McpSchema.Role;
+import org.springframework.ai.tool.metadata.ToolMetadata;
 import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
 
@@ -167,8 +168,11 @@ public static McpServerFeatures.SyncToolSpecification toSyncToolSpecification(To
 	 */
 	public static McpServerFeatures.SyncToolSpecification toSyncToolSpecification(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,
-				toolCallback.getToolMetadata().returnDirect());
+				returnDirect);
 
 		var tool = new McpSchema.Tool(toolCallback.getToolDefinition().name(),
 				toolCallback.getToolDefinition().description(), toolCallback.getToolDefinition().inputSchema(),

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

@@ -32,6 +32,7 @@
 import io.modelcontextprotocol.spec.McpSchema.TextContent;
 import io.modelcontextprotocol.spec.McpSchema.Tool;
 import org.junit.jupiter.api.Test;
+import org.springframework.ai.tool.metadata.ToolMetadata;
 import reactor.test.StepVerifier;
 
 import org.springframework.ai.tool.ToolCallback;
@@ -199,8 +200,10 @@ 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;
 	}
 
@@ -211,8 +214,10 @@ 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;
 	}