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Enterprise Java developers have a new superpower—drive GitHub Copilot from idiomatic Java code with annotations, virtual threads, and more.

August 10, 2026

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8 minutes

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Java developers no longer have to rely on Java framework-specific approaches to drive AI from their enterprise apps.

While it is true that Langchain4j empowered developers by disintermediating specific AI vendors, you still had a dependency on Langchain4j. And with Spring AI, well, of course you had a dependency on design choices made by Spring, if not on Spring itself.

Now, GitHub Copilot SDK for Java is the first truly framework agnostic way to drive AI from Java. And with its BYOK support, GitHub Copilot SDK for Java is also AI vendor neutral.

The GitHub Copilot SDK for Java is a client library that empowers your server-side Java code to create Copilot agent sessions, register tools, send prompts, and receive structured responses—all programmatically. It works in server environments, including Jakarta EE and Spring. If you’ve been building enterprise Java for any length of time, this SDK will feel like home: CompletableFuture, annotations, lambdas, virtual threads, it’s all here.

This post shows you how to use the SDK, walks through a complete Jakarta EE 11 sample application, and leaves you with concrete next steps to try it yourself. I chose Jakarta EE 11 for my demo because I was the lead release coordinator for that release. I believe in open standards as the best way to empower developers. For more on Jakarta EE 11 see this InfoQ article.

This sample app is an agent harness using Jakarta EE 11. But, of course, developers can build their own agent harness using the well-known Java frameworks and libraries of their choice.

Clone the sample app and try it yourself >

Where to get it

The SDK is available as a Maven dependency:

<dependency>
    <groupId>com.github</groupId>
    <artifactId>copilot-sdk-java</artifactId>
    <version>1.0.7-preview.1</version>
</dependency>

Prerequisites:

• JDK 17 or 25 (25 recommended — unlocks virtual threads and other modern features)
• Maven 3.9+
• A GitHub account with an active Copilot subscription
• The Copilot CLI installed locally at version 1.0.71 or later.

Walk through the sample app

The best way to see the SDK in action is to run this sample application.

Get the code

git clone https://github.com/microsoft/Build26-BRK206-your-agent-anywhere-multiclient-multidevice-with-github-copilot-sdk.git
cd Build26-BRK206-your-agent-anywhere-multiclient-multidevice-with-github-copilot-sdk/src/java-agent-orchestrator
mvn clean package liberty:run
# Open http://localhost:9080/index.xhtml

The Java demo is built on:

What the app does

The application is a real-estate lead-management agent pipeline. A customer submits an enquiry (“I’m looking for a 3-bedroom house in London under £800,000”), and the system spins up an isolated Copilot Agent on a virtual thread to process it through a pipeline:

The architecture uses Jakarta WebSocket to push real-time status updates from the server to the browser, so you can watch agents progress through phases as the model calls tools:

Submit multiple inquiries simultaneously to see concurrent virtual-thread agents in action. Each one processes independently with its own Copilot session.

SDK features in action

Let’s walk through the key SDK features as they appear in the sample code.

Defining tools with @CopilotTool

This is the headline API. If you’ve ever written a @GET endpoint in JAX-RS or an @MessageDriven bean, this will feel instantly familiar:

@CopilotTool(value = "Sets the current phase of the agent. Use this to report progress.",
             name = "set_current_phase")
public String setCurrentPhase(
        @CopilotToolParam("The phase to transition to (VALIDATING, SEARCHING, "
                + "WRITING_REPORT, REJECTED_GARBAGE, REJECTED_NO_MATCHES, or DONE)")
        String phaseName) {
    phase = Phase.valueOf(phaseName.trim().toUpperCase(Locale.ROOT));
    notifyUi();
    return "Phase set to " + phase.getLabel();
}

The @CopilotTool annotation declares the method as a tool the model can call. The @CopilotToolParam annotation describes each parameter so the model knows what to pass. The SDK handles all the JSON Schema generation, argument parsing, and dispatch. You just write a normal Java method.

Two build prerequisites for @CopilotTool. The annotation-based tool API is currently an experimental feature of the SDK, so you need to configure two things in your Maven build:

1. Enable experimental APIs: pass -Acopilot.experimental.allowed=true to the compiler. Without this flag, the annotation processor will refuse to generate the tool metadata. For more details on the experimental APIs see Copilot SDK documentation.
2. Register the annotation processor: add the SDK as an annotationProcessorPath so the compiler can find the @CopilotTool processor and generate the $$CopilotToolMeta classes at compile time.

Both are configured in the maven-compiler-plugin:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.15.0</version>
    <configuration>
        <compilerArgs>
            <arg>-Acopilot.experimental.allowed=true</arg>
        </compilerArgs>
        <annotationProcessorPaths>
            <path>
                <groupId>com.github</groupId>
                <artifactId>copilot-sdk-java</artifactId>
                <version>1.0.7-preview.1</version>
            </path>
        </annotationProcessorPaths>
    </configuration>
</plugin>

To register all annotated tools from an object:

List<ToolDefinition> annotatedTools = ToolDefinition.fromObject(this);

Inline lambda tools with ToolDefinition.from(...)

When you want a tool defined at the call site without a dedicated method, use the lambda style:

ToolDefinition reportIntentTool = ToolDefinition
        .from("report_intent",
              "Reports the current intent of the agent",
              Param.of(String.class, "intent", "Intent in max 4 words"),
              (String intent) -> {
                  currentIntent = intent;
                  addEvent(Instant.now(), "intent", "Intent updated", intent);
                  notifyUi();
                  return "ok";
              })
        .overridesBuiltInTool(true);

Notice .overridesBuiltInTool(true). This tells the SDK that our report_intent tool deliberately replaces a built-in tool of the same name. This is useful when you need custom behaviour for a tool the model already knows about.

Cross-class tool scanning

Tools don’t have to live in the same class as your agent logic. Here’s searchProperties defined in a separate CDI bean:

@ApplicationScoped
public class PropertyDatabase {

    @CopilotTool(value = "Searches the real estate listings database. "
                       + "Returns up to 10 matching properties.",
                 name = "search_properties")
    public List<Property> searchProperties(
            @CopilotToolParam("Property type substring (e.g. 'flat', 'house')") String type,
            @CopilotToolParam("City substring (e.g. 'London', 'Bristol')") String city,
            @CopilotToolParam("Minimum number of bedrooms (0 for no minimum)") int minBedrooms,
            @CopilotToolParam("Maximum price in GBP (0 for no maximum)") double maxPriceGbp) {
        // ... filter and return matching properties ...
    }
}

You would normally register these with ToolDefinition.fromObject(propertyDatabase). In the sample app, we use a lambda wrapper instead, because CDI client proxies can obscure the annotation metadata.

Customizing the system message

The SDK gives you fine-grained control over the system message. Use SystemMessageMode.CUSTOMIZE to replace specific sections while preserving the rest:

SystemMessageConfig systemMessage = new SystemMessageConfig()
        .setMode(SystemMessageMode.CUSTOMIZE)
        .setSections(Map.of(SystemMessageSections.IDENTITY,
            new SectionOverride()
                .setAction(SectionOverrideAction.REPLACE)
                .setContent("""
                    You are part of a real estate recommendation system.
                    You will receive enquiries from customers, and you must
                    carry out the following workflow...
                    """)));

The text block ("""...""") makes multi-line prompts readable without string concatenation. The IDENTITY section override replaces only the model’s self-description while leaving safety guardrails intact. If you prefer a simpler approach, SystemMessageMode.APPEND adds your content after the default system message without replacing anything.

The agentic loop: sendAndWait(...)

One line kicks off the full agentic loop:

session = client.createSession(sessionConfig).get();
// ...
AssistantMessageEvent result = session.sendAndWait(escapedEnquiry).get();

Behind .get(), the model reasons, calls your tools (potentially multiple times), and returns its final response. On a virtual thread, .get() is cheap. No platform thread is consumed while waiting. The SDK dispatches tool calls to your registered handlers automatically and feeds results back to the model until it’s done.

Real-time event handling with session.on(...)