Quarkus Model Context Protocol (MCP) Server

"Model Context Protocol (MCP) is an open protocol that enables seamless integration between LLM applications and external data sources and tools."

This extension provides declarative and programmatic APIs that enable developers to implement the MCP server features easily.

[!NOTE]
The LangChain4j project provides the MCP client functionality, either as a low-level programmatic API or as a full-fledged integration into AI-infused applications.

Get Started

Step #1

Add the following dependency to your POM file:

xml
<dependency>
    <groupId>io.quarkiverse.mcp</groupId>
    <!-- use 'quarkus-mcp-server-stdio' if you want to use the STDIO transport instead of the HTTP/SSE transport -->
    <artifactId>quarkus-mcp-server-sse</artifactId>
    <version>${project-version}</version>
</dependency>

Step #2

Add server features (prompts, resources and tools) represented by annotated business methods of CDI beans.

java
import jakarta.inject.Inject;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;

import io.quarkiverse.mcp.server.BlobResourceContents;
import io.quarkiverse.mcp.server.Prompt;
import io.quarkiverse.mcp.server.PromptArg;
import io.quarkiverse.mcp.server.PromptMessage;

import io.quarkiverse.mcp.server.Tool;
import io.quarkiverse.mcp.server.Resource;
import io.quarkiverse.mcp.server.TextContent;

// This class is automatically registered as a @Singleton CDI bean
public class ServerFeatures {

    @Inject
    CodeService codeService;

    @Tool(description = "Converts the string value to lower case")
    String toLowerCase(String value) {
        return value.toLowerCase();
    }

    @Prompt(name = "code_assist")
    PromptMessage codeAssist(@PromptArg(name = "lang") String language) {
        return PromptMessage.withUserRole(new TextContent(codeService.assist(language)));
    }

    @Resource(uri = "file:///project/alpha")
    BlobResourceContents alpha(RequestUri uri) throws IOException{
        return BlobResourceContents.create(uri.value(), Files.readAllBytes(Paths.ALPHA));
    }

}