Add rag utility

src/main/java/mcp/tools/McpValidatedTool.java

@@ -66,6 +66,17 @@ public abstract class McpValidatedTool implements McpTool {
         return new CallToolResultBuilder().addText(text).build();
     }
 
+    protected McpSchema.CallToolResult success(String text, Map<String, Object> structured) {
+        return new CallToolResultBuilder()
+                .addText(text)
+                .structuredContent(structured)
+                .build();
+    }
+
+    protected McpSchema.CallToolResult successResult(Object resultValue) {
+        return success(String.valueOf(resultValue), Map.of("result", resultValue));
+    }
+
     protected McpSchema.CallToolResult error(String text) {
         return new CallToolResultBuilder().isError(true).addText(text).build();
     }

src/test/java/mcp/registry/ToolRegistryTest.java

@@ -1,12 +1,13 @@
 package mcp.registry;
 
 import io.modelcontextprotocol.server.McpStatelessSyncServer;
-import io.modelcontextprotocol.spec.McpSchema;
 import mcp.tools.McpTool;
 import org.junit.jupiter.api.Test;
+
 import java.util.Set;
-import java.util.Map;
-import static org.junit.jupiter.api.Assertions.*;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.*;
 
 public class ToolRegistryTest {