feat(annotation): Introduce the annotations related to MCP prompt

Author: codeboyzhou

src/main/java/com/github/codeboyzhou/mcp/declarative/annotation/McpPrompt.java

@@ -0,0 +1,15 @@
+package com.github.codeboyzhou.mcp.declarative.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface McpPrompt {
+
+    String name() default "";
+
+    String description();
+}

src/main/java/com/github/codeboyzhou/mcp/declarative/annotation/McpPromptParam.java

@@ -0,0 +1,17 @@
+package com.github.codeboyzhou.mcp.declarative.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.PARAMETER)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface McpPromptParam {
+
+    String name();
+
+    String description();
+
+    boolean required() default false;
+}

src/main/java/com/github/codeboyzhou/mcp/declarative/annotation/McpPrompts.java

@@ -0,0 +1,11 @@
+package com.github.codeboyzhou.mcp.declarative.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface McpPrompts {
+}

src/main/java/com/github/codeboyzhou/mcp/declarative/server/McpServerComponentRegisters.java

@@ -1,5 +1,6 @@
 package com.github.codeboyzhou.mcp.declarative.server;
 
+import com.github.codeboyzhou.mcp.declarative.annotation.McpPrompts;
 import com.github.codeboyzhou.mcp.declarative.annotation.McpResources;
 import com.github.codeboyzhou.mcp.declarative.annotation.McpTools;
 import io.modelcontextprotocol.server.McpSyncServer;
@@ -13,6 +14,9 @@ public static void registerAllTo(McpSyncServer server, Reflections reflections)
         Set<Class<?>> resourceClasses = reflections.getTypesAnnotatedWith(McpResources.class);
         new McpSyncServerResourceRegister(resourceClasses).registerTo(server);
 
+        Set<Class<?>> promptClasses = reflections.getTypesAnnotatedWith(McpPrompts.class);
+        new McpSyncServerPromptRegister(promptClasses).registerTo(server);
+
         Set<Class<?>> toolClasses = reflections.getTypesAnnotatedWith(McpTools.class);
         new McpSyncServerToolRegister(toolClasses).registerTo(server);
     }

src/main/java/com/github/codeboyzhou/mcp/declarative/server/McpSyncServerPromptRegister.java

@@ -0,0 +1,75 @@
+package com.github.codeboyzhou.mcp.declarative.server;
+
+import com.github.codeboyzhou.mcp.declarative.annotation.McpPrompt;
+import com.github.codeboyzhou.mcp.declarative.annotation.McpPromptParam;
+import com.github.codeboyzhou.mcp.declarative.util.ReflectionHelper;
+import io.modelcontextprotocol.server.McpServerFeatures;
+import io.modelcontextprotocol.server.McpSyncServer;
+import io.modelcontextprotocol.spec.McpSchema;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+public class McpSyncServerPromptRegister
+    implements McpServerComponentRegister<McpSyncServer, McpServerFeatures.SyncPromptSpecification> {
+
+    private static final Logger logger = LoggerFactory.getLogger(McpSyncServerPromptRegister.class);
+
+    private final Set<Class<?>> promptClasses;
+
+    public McpSyncServerPromptRegister(Set<Class<?>> promptClasses) {
+        this.promptClasses = promptClasses;
+    }
+
+    @Override
+    public void registerTo(McpSyncServer server) {
+        for (Class<?> promptClass : promptClasses) {
+            Set<Method> methods = ReflectionHelper.getMethodsAnnotatedWith(promptClass, McpPrompt.class);
+            for (Method method : methods) {
+                McpServerFeatures.SyncPromptSpecification prompt = createComponentFrom(promptClass, method);
+                server.addPrompt(prompt);
+            }
+        }
+    }
+
+    @Override
+    public McpServerFeatures.SyncPromptSpecification createComponentFrom(Class<?> clazz, Method method) {
+        McpPrompt promptMethod = method.getAnnotation(McpPrompt.class);
+        final String name = promptMethod.name().isBlank() ? method.getName() : promptMethod.name();
+        final String description = promptMethod.description();
+        List<McpSchema.PromptArgument> promptArguments = createPromptArguments(method);
+        McpSchema.Prompt prompt = new McpSchema.Prompt(name, description, promptArguments);
+        return new McpServerFeatures.SyncPromptSpecification(prompt, (exchange, request) -> {
+            Object result;
+            try {
+                result = ReflectionHelper.invokeMethod(clazz, method, request.arguments());
+            } catch (Throwable e) {
+                logger.error("Error invoking prompt method", e);
+                result = e + ": " + e.getMessage();
+            }
+            McpSchema.Content content = new McpSchema.TextContent(result.toString());
+            McpSchema.PromptMessage message = new McpSchema.PromptMessage(McpSchema.Role.USER, content);
+            return new McpSchema.GetPromptResult(description, List.of(message));
+        });
+    }
+
+    private List<McpSchema.PromptArgument> createPromptArguments(Method method) {
+        Set<Parameter> parameters = ReflectionHelper.getParametersAnnotatedWith(method, McpPromptParam.class);
+        List<McpSchema.PromptArgument> promptArguments = new ArrayList<>(parameters.size());
+        for (Parameter parameter : parameters) {
+            McpPromptParam promptParam = parameter.getAnnotation(McpPromptParam.class);
+            final String name = promptParam.name();
+            final String description = promptParam.description();
+            final boolean required = promptParam.required();
+            McpSchema.PromptArgument promptArgument = new McpSchema.PromptArgument(name, description, required);
+            promptArguments.add(promptArgument);
+        }
+        return promptArguments;
+    }
+
+}

src/main/java/com/github/codeboyzhou/mcp/declarative/util/ReflectionHelper.java

@@ -28,6 +28,11 @@ public static Object invokeMethod(Class<?> clazz, Method method) throws Exceptio
         return method.invoke(object);
     }
 
+    public static Object invokeMethod(Class<?> clazz, Method method, Map<String, Object> parameters) throws Exception {
+        Object object = clazz.getDeclaredConstructor().newInstance();
+        return method.invoke(object, parameters.values().toArray());
+    }
+
     public static Object invokeMethod(Class<?> clazz, Method method, McpSchema.JsonSchema schema, Map<String, Object> parameters) throws Exception {
         Object object = clazz.getDeclaredConstructor().newInstance();
         Map<String, Object> typedParameters = asTypedParameters(schema, parameters);