Allows methods annotated with @tool to used @Blocking / @nonblocking …

…and @RunOnVirtualThread

core/deployment/pom.xml

@@ -102,6 +102,11 @@
                 </exclusion>
             </exclusions>
         </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-test-vertx</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
     <build>
         <plugins>

core/deployment/src/main/java/io/quarkiverse/langchain4j/deployment/AiServicesProcessor.java

@@ -8,6 +8,7 @@
 import static io.quarkiverse.langchain4j.deployment.LangChain4jDotNames.NO_RETRIEVAL_AUGMENTOR_SUPPLIER;
 import static io.quarkiverse.langchain4j.deployment.LangChain4jDotNames.NO_RETRIEVER;
 import static io.quarkiverse.langchain4j.deployment.LangChain4jDotNames.OUTPUT_GUARDRAILS;
+import static io.quarkiverse.langchain4j.deployment.LangChain4jDotNames.REGISTER_AI_SERVICES;
 import static io.quarkiverse.langchain4j.deployment.LangChain4jDotNames.SEED_MEMORY;
 import static io.quarkiverse.langchain4j.deployment.LangChain4jDotNames.V;
 import static io.quarkiverse.langchain4j.deployment.MethodParameterAsTemplateVariableAllowance.FORCE_ALLOW;
@@ -31,7 +32,6 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
-import java.util.concurrent.CompletionStage;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Predicate;
@@ -778,9 +778,9 @@ public boolean detectAiServiceMethodThanNeedToBeDispatchedOnWorkerThread(
             MethodInfo method,
             List<String> associatedTools,
             List<ToolMethodBuildItem> tools) {
-        boolean reactive = method.returnType().name().equals(DotName.createSimple(Uni.class.getName()))
-                || method.returnType().name().equals(DotName.createSimple(CompletionStage.class.getName()))
-                || method.returnType().name().equals(DotName.createSimple(Multi.class.getName()));
+        boolean reactive = method.returnType().name().equals(DotNames.UNI)
+                || method.returnType().name().equals(DotNames.COMPLETION_STAGE)
+                || method.returnType().name().equals(DotNames.MULTI);
 
         boolean requireSwitchToWorkerThread = false;
 
@@ -1260,8 +1260,8 @@ private AiServiceMethodCreateInfo gatherMethodMetadata(
 
         String accumulatorClassName = AiServicesMethodBuildItem.gatherAccumulator(method);
 
-        boolean switchToWorkerThread = detectAiServiceMethodThanNeedToBeDispatchedOnWorkerThread(method, methodToolClassNames,
-                tools);
+        //  Detect if tools execution may block the caller thread.
+        boolean switchToWorkerThread = detectIfToolExecutionRequiresAWorkerThread(method, tools, methodToolClassNames);
 
         return new AiServiceMethodCreateInfo(method.declaringClass().name().toString(), method.name(), systemMessageInfo,
                 userMessageInfo, memoryIdParamPosition, requiresModeration,
@@ -1270,6 +1270,20 @@ private AiServiceMethodCreateInfo gatherMethodMetadata(
                 inputGuardrails, outputGuardrails, accumulatorClassName);
     }
 
+    private boolean detectIfToolExecutionRequiresAWorkerThread(MethodInfo method, List<ToolMethodBuildItem> tools,
+            List<String> methodToolClassNames) {
+        List<String> allTools = new ArrayList<>(methodToolClassNames);
+        // We need to combine it with the tools that are registered globally - unfortunately, we don't have access to the AI service here, so, re-parsing.
+        AnnotationInstance annotation = method.declaringClass().annotation(REGISTER_AI_SERVICES);
+        if (annotation != null) {
+            AnnotationValue value = annotation.value("tools");
+            if (value != null) {
+                allTools.addAll(Arrays.stream(value.asClassArray()).map(t -> t.name().toString()).toList());
+            }
+        }
+        return detectAiServiceMethodThanNeedToBeDispatchedOnWorkerThread(method, allTools, tools);
+    }
+
     private void validateReturnType(MethodInfo method) {
         Type returnType = method.returnType();
         Type.Kind returnTypeKind = returnType.kind();

core/deployment/src/main/java/io/quarkiverse/langchain4j/deployment/DotNames.java

@@ -10,6 +10,7 @@
 
 import org.jboss.jandex.DotName;
 
+import dev.langchain4j.agent.tool.Tool;
 import dev.langchain4j.model.chat.listener.ChatModelListener;
 import io.smallrye.common.annotation.Blocking;
 import io.smallrye.common.annotation.NonBlocking;
@@ -54,4 +55,5 @@ public class DotNames {
     public static final DotName CDI_INSTANCE = DotName.createSimple(Instance.class);
 
     public static final DotName CHAT_MODEL_LISTENER = DotName.createSimple(ChatModelListener.class);
+    public static final DotName TOOL = DotName.createSimple(Tool.class);
 }

core/deployment/src/main/java/io/quarkiverse/langchain4j/deployment/ToolProcessor.java

@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.function.BiFunction;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 import org.jboss.jandex.AnnotationInstance;
@@ -68,6 +69,7 @@
 import io.quarkus.deployment.builditem.CombinedIndexBuildItem;
 import io.quarkus.deployment.builditem.GeneratedClassBuildItem;
 import io.quarkus.deployment.builditem.nativeimage.ReflectiveClassBuildItem;
+import io.quarkus.deployment.execannotations.ExecutionModelAnnotationsAllowedBuildItem;
 import io.quarkus.deployment.recording.RecorderContext;
 import io.quarkus.gizmo.ClassCreator;
 import io.quarkus.gizmo.ClassOutput;
@@ -263,6 +265,16 @@ public void handleTools(
         toolsMetadataProducer.produce(new ToolsMetadataBeforeRemovalBuildItem(metadata));
     }
 
+    @BuildStep
+    ExecutionModelAnnotationsAllowedBuildItem toolsMethods() {
+        return new ExecutionModelAnnotationsAllowedBuildItem(new Predicate<MethodInfo>() {
+            @Override
+            public boolean test(MethodInfo method) {
+                return method.hasDeclaredAnnotation(DotNames.TOOL);
+            }
+        });
+    }
+
     private void validateExecutionModel(ToolMethodCreateInfo methodCreateInfo, MethodInfo toolMethod,
             BuildProducer<ValidationPhaseBuildItem.ValidationErrorBuildItem> validation) {
         String methodName = toolMethod.declaringClass().name() + "." + toolMethod.name();

core/deployment/src/main/java/io/quarkiverse/langchain4j/deployment/items/ToolMethodBuildItem.java

@@ -6,6 +6,10 @@
 import io.quarkiverse.langchain4j.runtime.tool.ToolMethodCreateInfo;
 import io.quarkus.builder.item.MultiBuildItem;
 
+/**
+ * A build item that represents a method that is annotated with {@link dev.langchain4j.agent.tool.Tool}.
+ * It contains the method info and the tool method create info.
+ */
 public final class ToolMethodBuildItem extends MultiBuildItem {
 
     private final MethodInfo toolsMethodInfo;
@@ -33,13 +37,11 @@ public ToolMethodCreateInfo getToolMethodCreateInfo() {
      * Returns true if the method requires a switch to a worker thread, even if the method is non-blocking.
      * This is because of the tools executor limitation (imperative API).
      *
-     *
      * @return true if the method requires a switch to a worker thread
      */
     public boolean requiresSwitchToWorkerThread() {
         return !(toolMethodCreateInfo.executionModel() == ToolMethodCreateInfo.ExecutionModel.NON_BLOCKING
                 && isImperativeMethod());
-
     }
 
     private boolean isImperativeMethod() {