Tachyon MCP is a Java 21+ server runtime for the Model Context Protocol. It implements MCP 2025-11-25 and 2026-07-28 over Streamable HTTP and passes the official conformance suites for both versions.

Build servers with synchronous Java handlers or a coroutine-first Kotlin DSL. Tachyon runs blocking handlers on virtual threads, keeps them off the Netty event loop, and requires no application framework.

Why Tachyon?

• Simple handlers -- write blocking Java code or suspending Kotlin code without reactive pipelines or manual thread pools.
• Stable application API -- protocol-version mappers isolate handlers from wire-format changes.
• Java annotations support -- adapt existing mcp-java, LangChain4j, or Spring AI annotated services into Tachyon MCP servers.
• Stateless by default -- opt into sessions only when you need resumable SSE, event replay, and TTL cleanup.
• Production transport -- Netty backpressure, graceful shutdown, DNS-rebinding protection, CORS, and native transport auto-detection (io_uring → epoll → kqueue → NIO).
• Built-in OpenTelemetry -- register tachyon-opentelemetry's listener for MCP semantic-convention spans and metrics, with an opt-in policy for payload capture.

Quickstart

Import the BOM once to pin the version, then add the core dependency:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>dev.tachyonmcp</groupId>
            <artifactId>tachyon-bom</artifactId>
            <version>${tachyon.version}</version> <!-- get latest version from Maven Central -->
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>dev.tachyonmcp</groupId>
        <artifactId>tachyon-core</artifactId>
    </dependency>
</dependencies>

Create and start a server:

import dev.tachyonmcp.api.server.features.tools.ToolResult;
import dev.tachyonmcp.core.server.TachyonServer;

public class WeatherMcpServer {
    public static void main(String... args) {
        var server = TachyonServer.builder()
            .name("weather-mcp")
            .withTools(tools -> tools.register(
                tool -> tool.name("get_forecast")
                    .description("Get weather forecast")
                    .inputSchema("""
                        {"type":"object","properties":{"city":{"type":"string"}},"required":["city"]}
                        """),
                (context, request) -> ToolResult.text("☀️ 22°C")))
            .port(8080)
            .build();
        server.start();
    }
}

See the quickstart for Java and Kotlin examples plus a curl test.

Implemented features

Documentation and examples

• Configuration -- network, native I/O, sessions, CORS, and runtime limits
• Observability -- observation listeners, payload capture policy, and the bundled OpenTelemetry integration
• Tools, resources, and tasks -- feature APIs and examples
• Annotations -- mcp-java, LangChain4j, and Spring AI providers
• Extensions and MCP Skills -- custom protocol methods and SEP support
• Kotlin DSL -- builders, scopes, and suspending handlers
• Examples -- runnable Java and Kotlin servers
• FAQ -- frameworks, concurrency, deployment, and compatibility

Coding-agent skill

This repository also includes a skill that teaches coding agents how to build Tachyon servers. It is separate from the server-side SkillsExtension described above.

npx skills add tachyonmcp/tachyon --skill tachyon-mcp

Its Java and Kotlin examples are compiled during the project build to keep them current.

License

Tachyon MCP is available under the terms of the Apache 2.0.