Support no-args tools

Author: geoand

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

@@ -155,13 +155,6 @@ public void handleTools(CombinedIndexBuildItem indexBuildItem,
                         validationErrorFound = true;
                         continue;
                     }
-                    if (toolMethod.parametersCount() == 0) {
-                        validation.produce(
-                                new ValidationPhaseBuildItem.ValidationErrorBuildItem(new IllegalStateException(
-                                        "Tool method '" + toolMethod.name() + "' on class '" + className
-                                                + "' must have at least one parameter")));
-                        validationErrorFound = true;
-                    }
                     discoveredTools.put(toolMethod.name(), toolMethod.declaringClass());
 
                     if (Modifier.isPrivate(toolMethod.flags())) {
@@ -276,16 +269,19 @@ private static String generateInvoker(MethodInfo methodInfo, ClassOutput classOu
             MethodCreator invokeMc = classCreator.getMethodCreator(
                     MethodDescriptor.ofMethod(implClassName, "invoke", Object.class, Object.class, Object[].class));
 
-            ResultHandle[] targetMethodHandles = null;
-            if (methodInfo.parametersCount() != 0) {
+            ResultHandle result;
+            if (methodInfo.parametersCount() > 0) {
                 List<ResultHandle> argumentHandles = new ArrayList<>(methodInfo.parametersCount());
                 for (int i = 0; i < methodInfo.parametersCount(); i++) {
                     argumentHandles.add(invokeMc.readArrayValue(invokeMc.getMethodParam(1), i));
                 }
-                targetMethodHandles = argumentHandles.toArray(new ResultHandle[0]);
+                ResultHandle[] targetMethodHandles = argumentHandles.toArray(new ResultHandle[0]);
+                result = invokeMc.invokeVirtualMethod(MethodDescriptor.of(methodInfo), invokeMc.getMethodParam(0),
+                        targetMethodHandles);
+            } else {
+                result = invokeMc.invokeVirtualMethod(MethodDescriptor.of(methodInfo), invokeMc.getMethodParam(0));
             }
-            ResultHandle result = invokeMc.invokeVirtualMethod(MethodDescriptor.of(methodInfo), invokeMc.getMethodParam(0),
-                    targetMethodHandles);
+
             boolean toolReturnsVoid = methodInfo.returnType().kind() == Type.Kind.VOID;
             if (toolReturnsVoid) {
                 invokeMc.returnValue(invokeMc.load("Success"));

core/deployment/src/test/java/io/quarkiverse/langchain4j/test/ToolExecutorTest.java

@@ -11,6 +11,7 @@
 import org.jboss.shrinkwrap.api.ShrinkWrap;
 import org.jboss.shrinkwrap.api.spec.JavaArchive;
 import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
@@ -73,6 +74,11 @@ byte bytes(byte arg0, Byte arg1) {
         BigInteger bigIntegers(BigInteger arg0, BigInteger arg1) {
             return arg0.add(arg1);
         }
+
+        @Tool
+        int noArgs() {
+            return 1;
+        }
     }
 
     @ParameterizedTest
@@ -233,6 +239,18 @@ void should_execute_tool_with_parameters_of_type_BigInteger(String arguments) {
         executeAndAssert(arguments, "bigIntegers", "4");
     }
 
+    @Test
+    void should_execute_tool_with_no_args() {
+        ToolExecutionRequest request = ToolExecutionRequest.builder()
+                .build();
+
+        ToolExecutor toolExecutor = getToolExecutor("noArgs");
+
+        String result = toolExecutor.execute(request, null);
+
+        assertThat(result).isEqualTo("1");
+    }
+
     private void executeAndAssert(String arguments, String methodName,
             String expectedResult) {
         ToolExecutionRequest request = ToolExecutionRequest.builder()

core/runtime/src/main/java/io/quarkiverse/langchain4j/runtime/tool/QuarkusToolExecutor.java

@@ -2,6 +2,7 @@
 
 import java.lang.reflect.InvocationTargetException;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Map;
 import java.util.function.BiFunction;
 
@@ -111,6 +112,9 @@ private Object[] prepareArguments(ToolExecutionRequest toolExecutionRequest,
     }
 
     private Map<String, Object> convertJsonToArguments(String argumentsJsonStr) throws JsonProcessingException {
+        if (argumentsJsonStr == null || argumentsJsonStr.isEmpty()) {
+            return Collections.emptyMap();
+        }
         Mappable mappable = QuarkusJsonCodecFactory.ObjectMapperHolder.MAPPER.readValue(argumentsJsonStr, loadMapperClass());
         return mappable.obtainFieldValuesMap();
     }

openai/openai-vanilla/deployment/src/test/java/org/acme/examples/aiservices/ToolValidationTest.java

@@ -39,25 +39,6 @@ void test() {
         }
     }
 
-    @Nested
-    @DisplayName("No parameter detection")
-    class NoParameterTools {
-        @RegisterExtension
-        static final QuarkusUnitTest unitTest = new QuarkusUnitTest()
-                .setArchiveProducer(() -> ShrinkWrap.create(JavaArchive.class).addClasses(MyInvalidTool.class))
-                .assertException(t -> {
-                    assertThat(t)
-                            .isInstanceOf(DeploymentException.class)
-                            .hasCauseInstanceOf(IllegalStateException.class)
-                            .hasMessageContaining("Tool method 'myTool' on class");
-                });
-
-        @Test
-        void test() {
-            fail("Should not be called");
-        }
-    }
-
     @Nested
     @DisplayName("Abstract tool detection")
     class AbstractTools {