pyfagorass Java MCP Server Generator
Generate a complete, production-ready MCP server in Java using the official Java SDK with Maven or Gradle.
Project Generation
When asked to create a Java MCP server, generate a complete project with this structure:
my-mcp-server/
├── pom.xml (or build.gradle.kts)
├── src/
│ ├── main/
│ │ ├── java/
│ │ │ └── com/example/mcp/
│ │ │ ├── McpServerApplication.java
│ │ │ ├── config/
│ │ │ │ └── ServerConfiguration.java
│ │ │ ├── tools/
│ │ │ │ ├── ToolDefinitions.java
│ │ │ │ └── ToolHandlers.java
│ │ │ ├── resources/
│ │ │ │ ├── ResourceDefinitions.java
│ │ │ │ └── ResourceHandlers.java
│ │ │ └── prompts/
│ │ │ ├── PromptDefinitions.java
│ │ │ └── PromptHandlers.java
│ │ └── resources/
│ │ └── application.properties (if using Spring)
│ └── test/
│ └── java/
│ └── com/example/mcp/
│ └── McpServerTest.java
└── README.md
Maven pom.xml Template
<?xml version="1.0" encoding="UTF-8"?>
<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>
<groupId>com.example</groupId>
<artifactId>my-mcp-server</artifactId>
<version>1.0.0</version>
<packaging>jar</packaging>
<name>My MCP Server</name>
<description>Model Context Protocol server implementation</description>
<properties>
<java.version>17</java.version>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<mcp.version>0.14.1</mcp.version>
<slf4j.version>2.0.9</slf4j.version>
<logback.version>1.4.11</logback.version>
<junit.version>5.10.0</junit.version>
</properties>
<dependencies>
<!-- MCP Java SDK -->
<dependency>
<groupId>io.modelcontextprotocol.sdk</groupId>
<artifactId>mcp</artifactId>
<version>${mcp.version}</version>
</dependency>
<!-- Logging -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>${logback.version}</version>
</dependency>
<!-- Testing -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.projectreactor</groupId>
<artifactId>reactor-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.11.0</version>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>3.1.2</version>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.5.0</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>com.example.mcp.McpServerApplication</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Gradle build.gradle.kts Template
plugins {
id("java")
id("application")
}
group = "com.example"
version = "1.0.0"
java {
sourceCompatibility = JavaVersion.VERSION_17
targetCompatibility = JavaVersion.VERSION_17
}
repositories {
mavenCentral()
}
dependencies {
// MCP Java SDK
implementation("io.modelcontextprotocol.sdk:mcp:0.14.1")
// Logging
implementation("org.slf4j:slf4j-api:2.0.9")
implementation("ch.qos.logback:logback-classic:1.4.11")
// Testing
testImplementation("org.junit.jupiter:junit-jupiter:5.10.0")
testImplementation("io.projectreactor:reactor-test:3.5.0")
}
application {
mainClass.set("com.example.mcp.McpServerApplication")
}
tasks.test {
useJUnitPlatform()
}
McpServerApplication.java Template
package com.example.mcp;
import com.example.mcp.tools.ToolHandlers;
import com.example.mcp.resources.ResourceHandlers;
import com.example.mcp.prompts.PromptHandlers;
import io.mcp.server.McpServer;
import io.mcp.server.McpServerBuilder;
import io.mcp.server.transport.StdioServerTransport;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.Disposable;
public class McpServerApplication {
private static final Logger log = LoggerFactory.getLogger(McpServerApplication.class);
public static void main(String[] args) {
log.info("Starting MCP Server...");
try {
McpServer server = createServer();
StdioServerTransport transport = new StdioServerTransport();
// Start server
Disposable serverDisposable = server.start(transport).subscribe();
// Graceful shutdown
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
log.info("Shutting down MCP server");
serverDisposable.dispose();
server.stop().block();
}));
log.info("MCP Server started successfully");
// Keep running
Thread.currentThread().join();
} catch (Exception e) {
log.error("Failed to start MCP server", e);
System.exit(1);
}
}
private static McpServer createServer() {
McpServer server = McpServerBuilder.builder()
.serverInfo("my-mcp-server", "1.0.0")
.capabilities(capabilities -> capabilities
.tools(true)
.resources(true)
.prompts(true))
.build();
// Register handlers
ToolHandlers.register(server);
ResourceHandlers.register(server);
PromptHandlers.register(server);
return server;
}
}
ToolDefinitions.java Template
package com.example.mcp.tools;
import io.mcp.json.JsonSchema;
import io.mcp.server.tool.Tool;
import java.util.List;
public class ToolDefinitions {
public static List<Tool> getTools() {
return List.of(
createGreetTool(),
createCalculateTool()
);
}
private static Tool createGreetTool() {
return Tool.builder()
.name("greet")
.description("Generate a greeting message")
.inputSchema(JsonSchema.object()
.property("name", JsonSchema.string()
.description("Name to greet")
.required(true)))
.build();
}
private static Tool createCalculateTool() {
return Tool.builder()
.name("calculate")
.description("Perform mathematical calculations")
.inputSchema(JsonSchema.object()
.property("operation", JsonSchema.string()
.description("Operation to perform")
.enumValues(List.of("add", "subtract", "multiply", "divide"))
.required(true))
.property("a", JsonSchema.number()
.description("First operand")
.required(true))
.property("b", JsonSchema.number()
.description("Second operand")
.required(true)))
.build();
}
}
ToolHandlers.java Template
package com.example.mcp.tools;
import com.fasterxml.jackson.databind.JsonNode;
import io.mcp.server.McpServer;
import io.mcp.server.tool.ToolResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.publisher.Mono;
public class ToolHandlers {
private static final Logger log = LoggerFactory.getLogger(ToolHandlers.class);
public static void register(McpServer server) {
// Register tool list handler
server.addToolListHandler(() -> {
log.debug("Listing available tools");
return Mono.just(ToolDefinitions.getTools());
});
// Register greet handler
server.addToolHandler("greet", ToolHandlers::handleGreet);
// Register calculate handler
server.addToolHandler("calculate", ToolHandlers::handleCalculate);
}
private static Mono<ToolResponse> handleGreet(JsonNode arguments) {
log.info("Greet tool called");
if (!arguments.has("name")) {
return Mono.just(ToolResponse.error()
.message("Missing 'name' parameter")
.build());
}
String name = arguments.get("name").asText();
String greeting = "Hello, " + name + "! Welcome to MCP.";
log.debug("Generated greeting for: {}", name);
return Mono.just(ToolResponse.success()
.addTextContent(greeting)
.build());
}
private static Mono<ToolResponse> handleCalculate(JsonNode arguments) {
log.info("Calculate tool called");
if (!arguments.has("operation") || !arguments.has("a") || !arguments.has("b")) {
return Mono.just(ToolResponse.error()
.message("Missing required parameters")
.build());
}
String operation = arguments.get("operation").asText();
double a = arguments.get("a").asDouble();
double b = arguments.get("b").asDouble();
double result;
switch (operation) {
case "add":
result = a + b;
break;
case "subtract":
result = a - b;
break;
case "multiply":
result = a * b;
break;
case "divide":
if (b == 0) {
return Mono.just(ToolResponse.error()
.message("Division by zero")
.build());
}
result = a / b;
break;
default:
return Mono.just(ToolResponse.error()
.message("Unknown operation: " + operation)
.build());
}
log.debug("Calculation: {} {} {} = {}", a, operation, b, result);
return Mono.just(ToolResponse.success()
.addTextContent("Result: " + result)
.build());
}
}
ResourceDefinitions.java Template
package com.example.mcp.resources;
import io.mcp.server.resource.Resource;
import java.util.List;
public class ResourceDefinitions {
public static List<Resource> getResources() {
return List.of(
Resource.builder()
.name("Example Data")
.uri("resource://data/example")
.description("Example resource data")
.mimeType("application/json")
.build(),
Resource.builder()
.name("Configuration")
.uri("resource://config")
.description("Server configuration")
.mimeType("application/json")
.build()
);
}
}
ResourceHandlers.java Template
package com.example.mcp.resources;
import io.mcp.server.McpServer;
import io.mcp.server.resource.ResourceContent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.publisher.Mono;
import java.time.Instant;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class ResourceHandlers {
private static final Logger log = LoggerFactory.getLogger(ResourceHandlers.class);
private static final Map<String, Boolean> subscriptions = new ConcurrentHashMap<>();
public static void register(McpServer server) {
// Register resource list handler
server.addResourceListHandler(() -> {
log.debug("Listing available resources");
return Mono.just(ResourceDefinitions.getResources());
});
// Register resource read handler
server.addResourceReadHandler(ResourceHandlers::handleRead);
// Register resource subscribe handler
server.addResourceSubscribeHandler(ResourceHandlers::handleSubscribe);
// Register resource unsubscribe handler
server.addResourceUnsubscribeHandler(ResourceHandlers::handleUnsubscribe);
}
private static Mono<ResourceContent> handleRead(String uri) {
log.info("Reading resource: {}", uri);
switch (uri) {
case "resource://data/example":
String jsonData = String.format(
"{\"message\":\"Example resource data\",\"timestamp\":\"%s\"}",
Instant.now()
);
return Mono.just(ResourceContent.text(jsonData, uri, "application/json"));
case "resource://config":
String config = "{\"serverName\":\"my-mcp-server\",\"version\":\"1.0.0\"}";
return Mono.just(ResourceContent.text(config, uri, "application/json"));
default:
log.warn("Unknown resource requested: {}", uri);
return Mono.error(new IllegalArgumentException("Unknown resource URI: " + uri));
}
}
private static Mono<Void> handleSubscribe(String uri) {
log.info("Client subscribed to resource: {}", uri);
subscriptions.put(uri, true);
return Mono.empty();
}
private static Mono<Void> handleUnsubscribe(String uri) {
log.info("Client unsubscribed from resource: {}", uri);
subscriptions.remove(uri);
return Mono.empty();
}
}
PromptDefinitions.java Template
package com.example.mcp.prompts;
import io.mcp.server.prompt.Prompt;
import io.mcp.server.prompt.PromptArgument;
import java.util.List;
public class PromptDefinitions {
public static List<Prompt> getPrompts() {
return List.of(
Prompt.builder()
.name("code-review")
.description("Generate a code review prompt")
.argument(PromptArgument.builder()
.name("language")
.description("Programming language")
.required(true)
.build())
.argument(PromptArgument.builder()
.name("focus")
.description("Review focus area")
.required(false)
.build())
.build()
);
}
}
PromptHandlers.java Template
package com.example.mcp.prompts;
import io.mcp.server.McpServer;
import io.mcp.server.prompt.PromptMessage;
import io.mcp.server.prompt.PromptResult;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.publisher.Mono;
import java.util.List;
import java.util.Map;
public class PromptHandlers {
private static final Logger log = LoggerFactory.getLogger(PromptHandlers.class);
public static void register(McpServer server) {
// Register prompt list handler
server.addPromptListHandler(() -> {
log.debug("Listing available prompts");
return Mono.just(PromptDefinitions.getPrompts());
});
// Register prompt get handler
server.addPromptGetHandler(PromptHandlers::handleCodeReview);
}
private static Mono<PromptResult> handleCodeReview(String name, Map<String, String> arguments) {
log.info("Getting prompt: {}", name);
if (!name.equals("code-review")) {
return Mono.error(new IllegalArgumentException("Unknown prompt: " + name));
}
String language = arguments.getOrDefault("language", "Java");
String focus = arguments.getOrDefault("focus", "general quality");
String description = "Code review for " + language + " with focus on " + focus;
List<PromptMessage> messages = List.of(
PromptMessage.user("Please review this " + language + " code with focus on " + focus + "."),
PromptMessage.assistant("I'll review the code focusing on " + focus + ". Please share the code."),
PromptMessage.user("Here's the code to review: [paste code here]")
);
log.debug("Generated code review prompt for {} ({})", language, focus);
return Mono.just(PromptResult.builder()
.description(description)
.messages(messages)
.build());
}
}
McpServerTest.java Template
package com.example.mcp;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import io.mcp.server.McpServer;
import io.mcp.server.McpSyncServer;
import io.mcp.server.tool.ToolResponse;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;
class McpServerTest {
private McpSyncServer syncServer;
private ObjectMapper objectMapper;
@BeforeEach
void setUp() {
McpServer server = createTestServer();
syncServer = server.toSyncServer();
objectMapper = new ObjectMapper();
}
private McpServer createTestServer() {
// Same setup as main application
McpServer server = McpServerBuilder.builder()
.serverInfo("test-server", "1.0.0")
.capabilities(cap -> cap.tools(true))
.build();
// Register handlers
ToolHandlers.register(server);
return server;
}
@Test
void testGreetTool() {
ObjectNode args = objectMapper.createObjectNode();
args.put("name", "Java");
ToolResponse response = syncServer.callTool("greet", args);
assertFalse(response.isError());
assertEquals(1, response.getContent().size());
assertTrue(response.getContent().get(0).getText().contains("Java"));
}
@Test
void testCalculateTool() {
ObjectNode args = objectMapper.createObjectNode();
args.put("operation", "add");
args.put("a", 5);
args.put("b", 3);
ToolResponse response = syncServer.callTool("calculate", args);
assertFalse(response.isError());
assertTrue(response.getContent().get(0).getText().contains("8"));
}
@Test
void testDivideByZero() {
ObjectNode args = objectMapper.createObjectNode();
args.put("operation", "divide");
args.put("a", 10);
args.put("b", 0);
ToolResponse response = syncServer.callTool("calculate", args);
assertTrue(response.isError());
}
}
README.md Template
# My MCP Server
A Model Context Protocol server built with Java and the official MCP Java SDK.
## Features
- ✅ Tools: greet, calculate
- ✅ Resources: example data, configuration
- ✅ Prompts: code-review
- ✅ Reactive Streams with Project Reactor
- ✅ Structured logging with SLF4J
- ✅ Full test coverage
## Requirements
- Java 17 or later
- Maven 3.6+ or Gradle 7+
## Build
### Maven
```bash
mvn clean package
Gradle
./gradlew build
Run
Maven
java -jar target/my-mcp-server-1.0.0.jar
Gradle
./gradlew run
Testing
Maven
mvn test
Gradle
./gradlew test
Integration with Claude Desktop
Add to claude_desktop_config.json:
{
"mcpServers": {
"my-mcp-server": {
"command": "java",
"args": ["-jar", "/path/to/my-mcp-server-1.0.0.jar"]
}
}
}
License
MIT
## Generation Instructions
1. **Ask for project name and package**
2. **Choose build tool** (Maven or Gradle)
3. **Generate all files** with proper package structure
4. **Use Reactive Streams** for async handlers
5. **Include comprehensive logging** with SLF4J
6. **Add tests** for all handlers
7. **Follow Java conventions** (camelCase, PascalCase)
8. **Include error handling** with proper responses
9. **Document public APIs** with Javadoc
10. **Provide both sync and async** examples