Advancing Tool Support - Part 2

* Enhanced support for functions as tools via FunctionToolCallback (deprecating the existing FunctionInvokingFunctionCallback).
* Aligned JSON Schema generation and parsing logic between function-based and method-based tools.
* Deprecated previous client-side function calling APIs.
* Included AOT configuration for Tool-annotated methods in Spring beans.

Relates to gh-2049

Author: ThomasVitale

spring-ai-core/src/main/java/org/springframework/ai/aot/ToolBeanRegistrationAotProcessor.java

@@ -0,0 +1,79 @@
+/*
+ * 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.aot;
+
+import org.springframework.ai.tool.annotation.Tool;
+import org.springframework.aot.generate.GenerationContext;
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.ReflectionHints;
+import org.springframework.beans.factory.aot.BeanRegistrationAotContribution;
+import org.springframework.beans.factory.aot.BeanRegistrationAotProcessor;
+import org.springframework.beans.factory.aot.BeanRegistrationCode;
+import org.springframework.beans.factory.support.RegisteredBean;
+import org.springframework.core.annotation.MergedAnnotations;
+import org.springframework.lang.Nullable;
+import org.springframework.util.ReflectionUtils;
+
+import java.util.stream.Stream;
+
+import static org.springframework.core.annotation.MergedAnnotations.SearchStrategy.TYPE_HIERARCHY;
+
+/**
+ * AOT {@code BeanRegistrationAotProcessor} that detects the presence of the {@link Tool}
+ * annotation on methods and creates the required reflection hints.
+ *
+ * @author Thomas Vitale
+ * @since 1.0.0
+ */
+class ToolBeanRegistrationAotProcessor implements BeanRegistrationAotProcessor {
+
+	@Override
+	@Nullable
+	public BeanRegistrationAotContribution processAheadOfTime(RegisteredBean registeredBean) {
+		Class<?> beanClass = registeredBean.getBeanClass();
+		MergedAnnotations.Search search = MergedAnnotations.search(TYPE_HIERARCHY);
+
+		boolean hasAnyToolAnnotatedMethods = Stream.of(ReflectionUtils.getDeclaredMethods(beanClass))
+			.anyMatch(method -> search.from(method).isPresent(Tool.class));
+
+		if (hasAnyToolAnnotatedMethods) {
+			return new AotContribution(beanClass);
+		}
+
+		return null;
+	}
+
+	private static class AotContribution implements BeanRegistrationAotContribution {
+
+		private final MemberCategory[] memberCategories = new MemberCategory[] { MemberCategory.INVOKE_DECLARED_METHODS,
+				MemberCategory.INVOKE_PUBLIC_METHODS };
+
+		private final Class<?> toolClass;
+
+		public AotContribution(Class<?> toolClass) {
+			this.toolClass = toolClass;
+		}
+
+		@Override
+		public void applyTo(GenerationContext generationContext, BeanRegistrationCode beanRegistrationCode) {
+			ReflectionHints reflectionHints = generationContext.getRuntimeHints().reflection();
+			reflectionHints.registerType(toolClass, memberCategories);
+		}
+
+	}
+
+}

spring-ai-core/src/main/java/org/springframework/ai/aot/package-info.java

@@ -0,0 +1,22 @@
+/*
+ * 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.
+ */
+
+@NonNullApi
+@NonNullFields
+package org.springframework.ai.aot;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-ai-core/src/main/java/org/springframework/ai/model/function/AbstractFunctionCallback.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -25,6 +25,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import org.springframework.ai.chat.model.ToolContext;
+import org.springframework.ai.tool.function.FunctionToolCallback;
 import org.springframework.util.Assert;
 
 /**
@@ -41,7 +42,9 @@
  * @param <I> the 3rd party service input type.
  * @param <O> the 3rd party service output type.
  * @author Christian Tzolov
+ * @deprecated in favor of {@link FunctionToolCallback}.
  */
+@Deprecated
 abstract class AbstractFunctionCallback<I, O> implements BiFunction<I, ToolContext, O>, FunctionCallback {
 
 	private final String name;

spring-ai-core/src/main/java/org/springframework/ai/model/function/DefaultCommonCallbackInvokingSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024-2024 the original author or authors.
+ * Copyright 2024-2025 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.
@@ -26,9 +26,16 @@
 
 import org.springframework.ai.model.function.FunctionCallback.CommonCallbackInvokingSpec;
 import org.springframework.ai.model.function.FunctionCallback.SchemaType;
+import org.springframework.ai.tool.function.FunctionToolCallback;
+import org.springframework.ai.tool.method.MethodToolCallback;
 import org.springframework.ai.util.JacksonUtils;
 import org.springframework.util.Assert;
 
+/**
+ * @deprecated Use specific builder for the type of tool you need, e.g.
+ * {@link FunctionToolCallback.Builder} and {@link MethodToolCallback.Builder}.
+ */
+@Deprecated
 public class DefaultCommonCallbackInvokingSpec<B extends CommonCallbackInvokingSpec<B>>
 		implements CommonCallbackInvokingSpec<B> {
 

spring-ai-core/src/main/java/org/springframework/ai/model/function/DefaultFunctionCallbackBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -31,6 +31,8 @@
 import org.springframework.ai.model.function.FunctionCallback.FunctionInvokingSpec;
 import org.springframework.ai.model.function.FunctionCallback.MethodInvokingSpec;
 import org.springframework.ai.model.function.FunctionCallback.SchemaType;
+import org.springframework.ai.tool.function.FunctionToolCallback;
+import org.springframework.ai.tool.method.MethodToolCallback;
 import org.springframework.ai.util.ParsingUtils;
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.util.Assert;
@@ -42,7 +44,10 @@
  *
  * @author Christian Tzolov
  * @since 1.0.0
+ * @deprecated Use specific builder for the type of tool you need, e.g.
+ * {@link FunctionToolCallback.Builder} and {@link MethodToolCallback.Builder}.
  */
+@Deprecated
 public class DefaultFunctionCallbackBuilder implements FunctionCallback.Builder {
 
 	private static final Logger logger = LoggerFactory.getLogger(DefaultFunctionCallbackBuilder.class);

spring-ai-core/src/main/java/org/springframework/ai/model/function/DefaultFunctionCallingOptions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024-2024 the original author or authors.
+ * Copyright 2024-2025 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.
@@ -25,6 +25,7 @@
 import java.util.Set;
 
 import org.springframework.ai.chat.prompt.ChatOptions;
+import org.springframework.ai.model.tool.DefaultToolCallingChatOptions;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
@@ -35,7 +36,9 @@
  * @author Christian Tzolov
  * @author Thomas Vitale
  * @author Ilayaperumal Gopinathan
+ * @deprecated in favor of {@link DefaultToolCallingChatOptions}.
  */
+@Deprecated
 public class DefaultFunctionCallingOptions implements FunctionCallingOptions {
 
 	private List<FunctionCallback> functionCallbacks = new ArrayList<>();

spring-ai-core/src/main/java/org/springframework/ai/model/function/DefaultFunctionCallingOptionsBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024-2024 the original author or authors.
+ * Copyright 2024-2025 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.
@@ -22,6 +22,7 @@
 import java.util.Map;
 import java.util.Set;
 
+import org.springframework.ai.model.tool.DefaultToolCallingChatOptions;
 import org.springframework.util.Assert;
 
 /**
@@ -30,7 +31,9 @@
  * @author Christian Tzolov
  * @author Thomas Vitale
  * @author Ilayaperumal Gopinathan
+ * @deprecated in favor of {@link DefaultToolCallingChatOptions.Builder}.
  */
+@Deprecated
 public class DefaultFunctionCallingOptionsBuilder implements FunctionCallingOptions.Builder {
 
 	private final DefaultFunctionCallingOptions options;

spring-ai-core/src/main/java/org/springframework/ai/model/function/FunctionCallback.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -24,14 +24,19 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import org.springframework.ai.chat.model.ToolContext;
+import org.springframework.ai.tool.ToolCallback;
+import org.springframework.ai.tool.function.FunctionToolCallback;
+import org.springframework.ai.tool.method.MethodToolCallback;
 import org.springframework.core.ParameterizedTypeReference;
 
 /**
  * Represents a model function call handler. Implementations are registered with the
  * Models and called on prompts that trigger the function call.
  *
  * @author Christian Tzolov
+ * @deprecated in favor of {@link ToolCallback}.
  */
+@Deprecated
 public interface FunctionCallback {
 
 	/**
@@ -115,7 +120,11 @@ enum SchemaType {
 	 * <li>{@link FunctionInvokingSpec} - The function invoking builder interface.
 	 * <li>{@link MethodInvokingSpec} - The method invoking builder interface.
 	 * </ul>
+	 *
+	 * @deprecated Use specific builder for the type of tool you need, e.g.
+	 * {@link FunctionToolCallback.Builder} and {@link MethodToolCallback.Builder}.
 	 */
+	@Deprecated
 	interface Builder {
 
 		/**

spring-ai-core/src/main/java/org/springframework/ai/model/function/FunctionCallingOptions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -21,14 +21,17 @@
 import java.util.Set;
 
 import org.springframework.ai.chat.prompt.ChatOptions;
+import org.springframework.ai.model.tool.ToolCallingChatOptions;
 
 /**
  * FunctionCallingOptions is a set of options that can be used to configure the function
  * calling behavior of the ChatModel.
  *
  * @author Christian Tzolov
  * @author Ilayaperumal Gopinathan
+ * @deprecated in favor of {@link ToolCallingChatOptions}.
  */
+@Deprecated
 public interface FunctionCallingOptions extends ChatOptions {
 
 	/**

spring-ai-core/src/main/java/org/springframework/ai/model/function/FunctionInvokingFunctionCallback.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -23,6 +23,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import org.springframework.ai.chat.model.ToolContext;
+import org.springframework.ai.tool.function.FunctionToolCallback;
 import org.springframework.util.Assert;
 
 /**
@@ -34,7 +35,9 @@
  * @param <I> the input type
  * @param <O> the output type
  * @author Christian Tzolov
+ * @deprecated in favor of {@link FunctionToolCallback}.
  */
+@Deprecated
 public final class FunctionInvokingFunctionCallback<I, O> extends AbstractFunctionCallback<I, O> {
 
 	private final BiFunction<I, ToolContext, O> biFunction;