JBang and MCP stdio

.vscode_mcp.json

{
    "inputs": [
    {
      "type": "promptString",
      "id": "perplexity-key",
      "description": "Perplexity API Key",
      "password": true
    }
  ],
    "servers": {
        "underpants": {
            "type": "stdio",
            "command": "jbang",
            "args": [
                "C:\\Users\\robin\\IdeaProjects\\mcp-api-sdk\\mcp.java"
            ]
        }
    }
}

mcp.java

///usr/bin/env jbang "$0" "$@" ; exit $?
//DEPS io.modelcontextprotocol.sdk:mcp:0.10.0

import java.util.ArrayList;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.databind.ObjectMapper;

import io.modelcontextprotocol.server.McpServer;
import io.modelcontextprotocol.server.McpServerFeatures;
import io.modelcontextprotocol.server.McpSyncServer;
import io.modelcontextprotocol.server.transport.StdioServerTransportProvider;
import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
import io.modelcontextprotocol.spec.McpSchema.GetPromptResult;
import io.modelcontextprotocol.spec.McpSchema.Prompt;
import io.modelcontextprotocol.spec.McpSchema.PromptArgument;
import io.modelcontextprotocol.spec.McpSchema.PromptMessage;
import io.modelcontextprotocol.spec.McpSchema.ReadResourceResult;
import io.modelcontextprotocol.spec.McpSchema.Resource;
import io.modelcontextprotocol.spec.McpSchema.ResourceContents;
import io.modelcontextprotocol.spec.McpSchema.Role;
import io.modelcontextprotocol.spec.McpSchema.ServerCapabilities;
import io.modelcontextprotocol.spec.McpSchema.TextContent;
import io.modelcontextprotocol.spec.McpSchema.TextResourceContents;
import io.modelcontextprotocol.spec.McpSchema.Tool;

/**
 * https://code.visualstudio.com/docs/copilot/chat/mcp-servers
 * https://code.visualstudio.com/mcp
 */
public class mcp {

    private static final Logger log = LoggerFactory.getLogger(mcp.class);

    public static void main(String... args) {

        log.info("starting my mcp service");

        StdioServerTransportProvider transportProvider
         = new StdioServerTransportProvider(new ObjectMapper());

        McpSyncServer syncServer = McpServer.sync(transportProvider)
                .serverInfo("my-server", "1.0.0")
                .capabilities(ServerCapabilities.builder()
                        .resources(false, true)
                        .tools(true)
                        .prompts(true)
                        // .logging()
                        // .completions()
                        .build())
                .build();

        String schema = """
                {
                    "type" : "object",
                    "id" : "urn:jsonschema:Operation",
                    "properties" : {}
                }
                """;;
        var syncToolSpecification = new McpServerFeatures.SyncToolSpecification(
            new Tool("funny", "captain underpants facts.", schema),
            (exchange,arguments)  -> {
                log.info("my tool has been called");
                // tool impl
                return new CallToolResult("he is really mr krupps", false);
            });

        syncServer.addTool(syncToolSpecification);

        // Sync resource specification
        var syncResourceSpecification = new McpServerFeatures.SyncResourceSpecification(
            new Resource("jokes", "captain underpants jokes", "a list of captain underpants jokes", "text/plain", null),
            (exchange, request) -> {
                log.info("my resource has been accessedd");
                List<ResourceContents> contents = new ArrayList<>();
                contents.add(new TextResourceContents("joke1", "text/plain", "knock knock"));
                contents.add(new TextResourceContents("joke2", "text/plain", "waitier watier"));
                // Resource read implementation
                return new ReadResourceResult(contents);
            }
        );

        syncServer.addResource(syncResourceSpecification);

        // Sync prompt specification
var syncPromptSpecification = new McpServerFeatures.SyncPromptSpecification(
    new Prompt("greeting", "a prompt for sending greetings", List.of(
        new PromptArgument("name", "name of the person to send greetings to", true)
    )),
    (exchange, request) -> {
        log.info("my rpomt has been accessedd");
        List<PromptMessage> messages = new ArrayList<>();
        messages.add(new PromptMessage( 
            Role.USER, 
            new TextContent( "talk about flowers")
        ));
        // Prompt implementation
        return new GetPromptResult("prompt for another greeting", messages);
    }
);
        
syncServer.addPrompt(syncPromptSpecification);

       log.info("Hello World");

        // Add shutdown hook to close the server gracefully
        Runtime.getRuntime().addShutdownHook(new Thread(() -> {
            syncServer.close();
            log.info("Server stopped.");
        }));

        log.info("waiting for requests");

        // Block main thread to keep the server running as a daemon
        Object lock = new Object();
        try {
            synchronized (lock) {
                lock.wait();
            }
        } catch (InterruptedException e) {
            // Exit on interrupt
        }
    }

}