- New version of Calendar app using declarative

- Add support for service injection in MCP server class
- Fix problem binding lists to method params
- Few other minor fixes
- Update README for new app

Author: spericas

codegen/src/main/java/io/helidon/extensions/mcp/codegen/McpCodegen.java

@@ -32,6 +32,7 @@
 import io.helidon.codegen.RoundContext;
 import io.helidon.codegen.classmodel.ClassModel;
 import io.helidon.codegen.classmodel.Method;
+import io.helidon.codegen.classmodel.Parameter;
 import io.helidon.codegen.spi.CodegenExtension;
 import io.helidon.common.types.AccessModifier;
 import io.helidon.common.types.Annotation;
@@ -44,6 +45,7 @@
 import io.helidon.common.types.TypeNames;
 import io.helidon.common.types.TypedElementInfo;
 
+import static io.helidon.common.types.TypeNames.LIST;
 import static io.helidon.extensions.mcp.codegen.McpJsonSchemaCodegen.addSchemaMethodBody;
 import static io.helidon.extensions.mcp.codegen.McpJsonSchemaCodegen.getDescription;
 import static io.helidon.extensions.mcp.codegen.McpTypes.CONSUMER_REQUEST;
@@ -96,7 +98,7 @@
 
 final class McpCodegen implements CodegenExtension {
     private static final TypeName GENERATOR = TypeName.create(McpCodegen.class);
-    private static final ResolvedType STRING_LIST = ResolvedType.create(TypeName.builder(TypeNames.LIST)
+    private static final ResolvedType STRING_LIST = ResolvedType.create(TypeName.builder(LIST)
                                                                                 .addTypeArgument(TypeNames.STRING)
                                                                                 .build());
 
@@ -148,12 +150,25 @@ private void process(RoundContext roundCtx, TypeInfo type) {
 
         serverClassModel.addField(delegate -> delegate
                 .accessModifier(AccessModifier.PRIVATE)
-                .isFinal(true)
-                .name("delegate")
                 .type(type.typeName())
-                .addContent("new ")
-                .addContent(type.typeName())
-                .addContent("()"));
+                .name("delegate"));
+
+        serverClassModel.addImport("io.helidon.service.registry.GlobalServiceRegistry");
+
+        serverClassModel.addConstructor(constructor -> {
+            constructor.accessModifier(AccessModifier.PUBLIC);
+            constructor.addContentLine("try {")
+                    .addContent("delegate = GlobalServiceRegistry.registry().get(")
+                    .addContent(type.typeName())
+                    .addContentLine(".class);")
+                    .decreaseContentPadding()
+                    .addContentLine("} catch (Exception e) {")
+                    .addContent("delegate = ")
+                    .addContent("new ")
+                    .addContent(type.typeName())
+                    .addContentLine("();")
+                    .addContentLine("}");
+        });
 
         generateTools(generatedType, serverClassModel, type);
         generatePrompts(generatedType, serverClassModel, type);
@@ -440,10 +455,15 @@ private void addResourceMethod(Method.Builder builder, String uri, ClassModel.Bu
                 if (TypeNames.STRING.equals(parameter.typeName())) {
                     parameters.add(parameter.elementName());
                     builder.addContent("String ")
-                            .addContent(parameter.elementName())
+                            .addContent("encoded_" + parameter.elementName())
                             .addContent(" = request.parameters().get(\"")
                             .addContent(parameter.elementName())
                             .addContentLine("\").asString().orElse(\"\");");
+                    builder.addContent("String ")
+                            .addContent(parameter.elementName())
+                            .addContent(" = io.helidon.common.uri.UriPath.create(")
+                            .addContent("encoded_" + parameter.elementName())
+                            .addContentLine(").path();");
                 }
             }
         }
@@ -620,7 +640,7 @@ private void addPromptArgumentsMethod(Method.Builder builder, TypedElementInfo e
                 .returnType(LIST_MCP_PROMPT_ARGUMENT);
 
         for (TypedElementInfo param : element.parameterArguments()) {
-            if (MCP_FEATURES.equals(param.typeName())) {
+            if (isIgnoredSchemaElement(param.typeName())) {
                 continue;
             }
             String builderName = "builder" + index++;
@@ -812,6 +832,22 @@ private void addToolMethod(Method.Builder builder, ClassModel.Builder classModel
                         .addContentLine("().orElse(null);");
                 continue;
             }
+            if (isList(param.typeName())) {
+                TypeName typeArg = param.typeName().typeArguments().getFirst();
+                addToListMethod(classModel, typeArg);
+
+                if (!parametersLocalVar) {
+                    addParametersLocalVar(builder, classModel);
+                    parametersLocalVar = true;
+                }
+                parameters.add(param.elementName());
+                builder.addContent("var ")
+                        .addContent(param.elementName())
+                        .addContent(" = toList(parameters.get(\"")
+                        .addContent(param.elementName())
+                        .addContentLine("\").asList().orElse(null));");
+                continue;
+            }
             if (!parametersLocalVar) {
                 addParametersLocalVar(builder, classModel);
                 parametersLocalVar = true;
@@ -975,6 +1011,23 @@ private void addSubscriberMethod(Method.Builder builder, TypedElementInfo elemen
                 .addContentLine("};");
     }
 
+    private void addToListMethod(ClassModel.Builder classModel, TypeName type) {
+        Method.Builder method = Method.builder();
+        TypeName typeList = TypeName.create("java.util.List<" + type + ">");
+        TypeName parameterList = TypeName.create("java.util.List<" + MCP_PARAMETERS + ">");
+        method.name("toList")
+                .isStatic(true)
+                .accessModifier(AccessModifier.PRIVATE)
+                .returnType(typeList);
+        method.addParameter(Parameter.builder().name("list").type(parameterList).build());
+        method.addContentLine("return list == null ? List.of()");
+        method.increaseContentPadding();
+        method.addContentLine(": list.stream().map(p -> p.as(" + type + ".class))");
+        method.increaseContentPadding();
+        method.addContentLine(".map(p -> p.get()).toList();");
+        classModel.addMethod(method.build());
+    }
+
     private boolean isBoolean(TypeName type) {
         return TypeNames.PRIMITIVE_BOOLEAN.equals(type) || TypeNames.BOXED_BOOLEAN.equals(type);
     }
@@ -994,6 +1047,10 @@ private boolean isNumber(TypeName type) {
                 || TypeNames.PRIMITIVE_DOUBLE.equals(type);
     }
 
+    private boolean isList(TypeName type) {
+        return type.equals(TypeNames.LIST) && type.typeArguments().size() == 1;
+    }
+
     private TypeName createClassName(TypeName generatedType, TypedElementInfo element, String suffix) {
         return TypeName.builder()
                 .className(element.findAnnotation(MCP_NAME)

codegen/src/main/java/io/helidon/extensions/mcp/codegen/McpJsonSchemaCodegen.java

@@ -87,7 +87,7 @@ private static void addPropertySchema(Method.Builder method, TypedElementInfo el
             TypeName argument = typeName.boxed().typeArguments().getFirst();
             method.addContent("builder.append(\"\\\"")
                     .addContent(element.elementName())
-                    .addContentLine("\\\"\": {\");");
+                    .addContentLine("\\\": {\");");
 
             description.ifPresent(desc -> addDescription(method, desc));
 

etc/checkstyle-suppressions.xml

@@ -21,6 +21,6 @@
         "-//Puppy Crawl//DTD Suppressions 1.1//EN"
         "http://checkstyle.sourceforge.net/dtds/suppressions_1_1.dtd">
 <suppressions>
-    <!-- Suppress visibility checks for @Mcp.JsonSchema annotated classes -->
+    <suppress files="examples/calendar-application/calendar-declarative/src/main/java/.*" checks="VisibilityModifier"/>
     <suppress files="tests/declarative/src/main/java/.*" checks="VisibilityModifier"/>
 </suppressions>

examples/calendar-application/README.md

@@ -1,6 +1,6 @@
 # Helidon MCP Calendar Application
 
-This application serves as a calendar manager and demonstrates how to utilize the MCP Inspector for debugging an MCP server.
+This application serves as a calendar manager and demonstrates how to use the MCP Inspector for debugging an MCP server.
 It allows you to create events and view them through a single registered resource. The calendar is basic and has a single usage: 
 record created events.
 
@@ -18,7 +18,7 @@ Build and launch the calendar application using the following commands:
 
 ```shell
 mvn clean package
-java -jar target/helidon-mcp-calendar-server.jar
+java -jar target/helidon-calendar-declarative.jar
 ```
 
 ## Using the MCP Inspector
@@ -34,39 +34,42 @@ MCP server:
 ### Testing the Tool
 
 1. Navigate to the **Tool** tab.
-2. Click **List Tools** and select the first tool from the list.
+2. Click **List Tools** and select the `addCalendarEventTool` tool from the list.
 3. Enter the following parameters on the right panel:
 
-    * **Name**: Franck-birthday
+    * **Name**: Frank birthday
     * **Date**: 2021-04-20
-    * **Attendees**: CLick `switch to JSON` and enter `["Franck"]`.
+    * **Attendees**: Click `switch to JSON` and enter `["Frank"]`.
 4. Click **Run Tool**.
-5. You should see the message: `New event added to the calendar.`
+5. You should see the message: `New event added to the calendar`
 
 ### Testing the Resource
 
 1. Navigate to the **Resource** tab.
 2. Click **List Resources**.
 3. Select the first resource in the list.
-4. Verify that the result displayed includes Franck's birthday event.
+4. Verify that the result displayed includes Frank's birthday event.
 
 ### Testing the Resource Template
 
 1. Navigate to the **Resource** tab.
 2. Click **List Resources Template**.
-3. Enter `calendar` as path.
-4. Verify that the result displayed includes Franck's birthday event.
+3. Select `eventResourceTemplate`.
+3. Type `F` for the name to trigger completion.
+4. Select `Frank birthday` from pop-up menu.
+5. Click `Read Resource`.
+4. Verify that the result displayed includes Frank's birthday event.
 
 ### Testing the Prompt
 
-1. Navigate to the **Prompt** tab.
-2. Click **List Prompt**.
+1. Navigate to the **Prompts** tab.
+2. Click **List Prompts**.
 3. Select the first Prompt in the list.
 4. Enter the following parameters on the right panel:
 
-    * **Name**: Franck-birthday
+    * **Name**: Frank birthday
     * **Date**: 2021-04-20
-    * **Attendees**: Franck
+    * **Attendees**: Frank
 5. Click **Get Prompt**
 
 ## References

examples/calendar-application/calendar-declarative/pom.xml

@@ -1,22 +1,39 @@
 <?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright (c) 2025 Oracle and/or its affiliates.
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+-->
 <project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <parent>
-        <groupId>io.helidon.extensions.mcp</groupId>
-        <artifactId>helidon4-extensions-mcp-project</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
+        <groupId>io.helidon.applications</groupId>
+        <artifactId>helidon-se</artifactId>
+        <version>4.3.1</version>
         <relativePath/>
     </parent>
 
     <groupId>io.helidon.extensions.mcp.examples</groupId>
     <artifactId>helidon4-extensions-mcp-examples-calendar-declarative</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
     <name>Helidon 4 Extensions MCP Calendar Example Declarative</name>
 
-
     <properties>
-        <mainClass>io.helidon.extensions.mcp.examples.calendar.Main</mainClass>
+        <mainClass>io.helidon.extensions.mcp.examples.calendar.declarative.Main</mainClass>
         <version.lib.mcp-sdk>0.11.3</version.lib.mcp-sdk>
     </properties>
 

examples/calendar-application/calendar-declarative/src/main/java/io/helidon/extensions/mcp/examples/calendar/declarative/Calendar.java

@@ -21,6 +21,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
@@ -33,17 +34,14 @@
  */
 @Service.Singleton
 final class Calendar {
-    static final String URI_TEMPLATE = "file://events/{name}";
 
     private final Path file;
     private final String uri;
-    private final String uriTemplate;
 
     Calendar() {
         try {
             this.file = Files.createTempFile("calendar", "-calendar");
             this.uri = file.toUri().toString();
-            this.uriTemplate = URI_TEMPLATE;
         } catch (IOException ex) {
             throw new UncheckedIOException(ex);
         }
@@ -53,10 +51,6 @@ String uri() {
         return uri;
     }
 
-    String uriTemplate() {
-        return uriTemplate;
-    }
-
     String readContent() {
         try {
             return Files.readString(file);
@@ -76,6 +70,22 @@ String readContentMatchesLine(Predicate<String> lineMatcher) {
         }
     }
 
+    List<String> readEventNames() {
+        String prefix = "name: ";
+        List<String> values = new ArrayList<>();
+        String contents = readContent();
+        for (int i = 0; i < contents.length();) {
+            int k = contents.indexOf(prefix, i);
+            if (k == -1) {
+                break;
+            }
+            int j = contents.indexOf(", ", k);
+            values.add(contents.substring(k + prefix.length(), j));
+            i = j + 1;
+        }
+        return values;
+    }
+
     void createNewEvent(String name, String date, List<String> attendees) {
         try {
             String content = String.format("Event: { name: %s, date: %s, attendees: %s }\n", name, date, attendees);