Issue 3924 Fix MethodToolCallback enum argument handling

spring-ai-model/src/main/java/org/springframework/ai/tool/method/MethodToolCallback.java

@@ -104,7 +104,15 @@ public String call(String toolInput, @Nullable ToolContext toolContext) {
 
 		Map<String, Object> toolArguments = extractToolArguments(toolInput);
 
-		Object[] methodArguments = buildMethodArguments(toolArguments, toolContext);
+		Object[] methodArguments;
+		try {
+			methodArguments = buildMethodArguments(toolArguments, toolContext);
+		}
+		catch (IllegalArgumentException ex) {
+			logger.debug("Failed to build method arguments for tool: {}. Error: {}", this.toolDefinition.name(),
+					ex.getMessage());
+			throw new ToolExecutionException(this.toolDefinition, ex);
+		}
 
 		Object result = callMethod(methodArguments);
 

spring-ai-model/src/test/java/org/springframework/ai/tool/method/MethodToolCallbackTests.java

@@ -0,0 +1,104 @@
+
+/*
+ * Copyright 2023-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.tool.method;
+
+import java.lang.reflect.Method;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.ai.tool.annotation.Tool;
+import org.springframework.ai.tool.definition.DefaultToolDefinition;
+import org.springframework.ai.tool.definition.ToolDefinition;
+import org.springframework.ai.tool.execution.ToolExecutionException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+/**
+ * Unit tests for {@link MethodToolCallback}.
+ *
+ * @author Thomas Vitale
+ */
+class MethodToolCallbackTests {
+
+	@Test
+	void shouldThrowToolExecutionExceptionForInvalidEnumArgument() throws Exception {
+		// Given
+		TestToolClass testTool = new TestToolClass();
+		Method method = TestToolClass.class.getDeclaredMethod("processOrder", OrderType.class);
+		ToolDefinition toolDefinition = DefaultToolDefinition.builder()
+			.name("processOrder")
+			.description("Process an order")
+			.inputSchema("{}")
+			.build();
+
+		MethodToolCallback callback = new MethodToolCallback(toolDefinition, null, method, testTool, null);
+
+		// When/Then - Invalid enum value should throw ToolExecutionException
+		assertThatThrownBy(() -> callback.call("{\"orderType\": \"INVALID_TYPE\"}"))
+			.isInstanceOf(ToolExecutionException.class)
+			.hasCauseInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("No enum constant");
+
+		// Verify the ToolExecutionException contains the correct tool definition
+		try {
+			callback.call("{\"orderType\": \"INVALID_TYPE\"}");
+		}
+		catch (ToolExecutionException ex) {
+			assertThat(ex.getToolDefinition()).isEqualTo(toolDefinition);
+			assertThat(ex.getCause()).isInstanceOf(IllegalArgumentException.class);
+		}
+	}
+
+	@Test
+	void shouldSucceedWithValidEnumArgument() throws Exception {
+		// Given
+		TestToolClass testTool = new TestToolClass();
+		Method method = TestToolClass.class.getDeclaredMethod("processOrder", OrderType.class);
+		ToolDefinition toolDefinition = DefaultToolDefinition.builder()
+			.name("processOrder")
+			.description("Process an order")
+			.inputSchema("{}")
+			.build();
+
+		MethodToolCallback callback = new MethodToolCallback(toolDefinition, null, method, testTool, null);
+
+		// When
+		String result = callback.call("{\"orderType\": \"ONE_DAY\"}");
+
+		// Then
+		assertThat(result).isEqualTo("\"Processing ONE_DAY order\"");
+	}
+
+	// Test classes
+	static class TestToolClass {
+
+		@Tool(description = "Process an order with the specified delivery type")
+		public String processOrder(OrderType orderType) {
+			return "Processing " + orderType + " order";
+		}
+
+	}
+
+	enum OrderType {
+
+		ONE_DAY, TWO_DAY, THREE_DAY
+
+	}
+
+}