Advancing Tool Support - Part 1

* Defined new APIs consolidating the “tool” naming as opposed to the current “function”, aligning with the industry and solving the confusion between “function tool” and “Java Function”: ToolCallback and ToolCallingChatOptions. They extend the current ones to ensure backward compatibility, but FunctionCallback and FunctionCallingOptions can be considered deprecated.
* Enhanced support for methods as tools, introducing support for declarative Tool-annotated methods via MethodToolCallback and MethodToolCallbackProvider (deprecating the existing MethodInvokingFunctionCallback).
* Improved tool execution logic with granular support for returning the result directly to the client and exception handling.
* Improved JSON Schema generation and parsing logic, consolidating the usage of the victools/jsonschema-generator library and dropping the non-maintained Jackson JSON Schema Module. This makes it possible to use tools with input lists/arrays, which the latter library was not supporting.
* Extended ChatClient API with new methods tools() and toolCallbacks(). The existing functions() methods can be considered deprecated.

Relates to gh-2049

Signed-off-by: Thomas Vitale <ThomasVitale@users.noreply.github.com>

Author: ThomasVitale

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

@@ -0,0 +1,39 @@
+/*
+ * 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.execution.DefaultToolCallResultConverter;
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.RuntimeHintsRegistrar;
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
+
+/**
+ * Registers runtime hints for the tool calling APIs.
+ *
+ * @author Thomas Vitale
+ */
+public class ToolRuntimeHints implements RuntimeHintsRegistrar {
+
+	@Override
+	public void registerHints(@NonNull RuntimeHints hints, @Nullable ClassLoader classLoader) {
+		var mcs = MemberCategory.values();
+		hints.reflection().registerType(DefaultToolCallResultConverter.class, mcs);
+	}
+
+}

spring-ai-core/src/main/java/org/springframework/ai/chat/client/ChatClient.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.
@@ -215,6 +215,12 @@ interface ChatClientRequestSpec {
 
 		<T extends ChatOptions> ChatClientRequestSpec options(T options);
 
+		ChatClientRequestSpec tools(String... toolNames);
+
+		ChatClientRequestSpec tools(Object... toolObjects);
+
+		ChatClientRequestSpec toolCallbacks(FunctionCallback... toolCallbacks);
+
 		/**
 		 * @deprecated use {@link #functions(FunctionCallback...)} instead.
 		 */
@@ -293,6 +299,12 @@ interface Builder {
 
 		Builder defaultSystem(Consumer<PromptSystemSpec> systemSpecConsumer);
 
+		Builder defaultTools(String... toolNames);
+
+		Builder defaultTools(Object... toolObjects);
+
+		Builder defaultToolCallbacks(FunctionCallback... toolCallbacks);
+
 		/**
 		 * @deprecated use {@link #defaultFunctions(FunctionCallback...)} instead.
 		 */

spring-ai-core/src/main/java/org/springframework/ai/chat/client/DefaultChatClient.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.
@@ -32,6 +32,7 @@
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationRegistry;
 import io.micrometer.observation.contextpropagation.ObservationThreadLocalAccessor;
+import org.springframework.ai.tool.ToolCallbacks;
 import reactor.core.publisher.Flux;
 import reactor.core.scheduler.Schedulers;
 
@@ -782,10 +783,9 @@ public Builder mutate() {
 				builder.defaultOptions(this.chatOptions);
 			}
 
-			// workaround to set the missing fields.
-			builder.defaultRequest.getMessages().addAll(this.messages);
-			builder.defaultRequest.getFunctionCallbacks().addAll(this.functionCallbacks);
-			builder.defaultRequest.getToolContext().putAll(this.toolContext);
+			builder.addMessages(this.messages);
+			builder.addToolCallbacks(this.functionCallbacks);
+			builder.addToolContext(this.toolContext);
 
 			return builder;
 		}
@@ -836,6 +836,30 @@ public <T extends ChatOptions> ChatClientRequestSpec options(T options) {
 			return this;
 		}
 
+		@Override
+		public ChatClientRequestSpec tools(String... toolNames) {
+			Assert.notNull(toolNames, "toolNames cannot be null");
+			Assert.noNullElements(toolNames, "toolNames cannot contain null elements");
+			this.functionNames.addAll(List.of(toolNames));
+			return this;
+		}
+
+		@Override
+		public ChatClientRequestSpec tools(Object... toolObjects) {
+			Assert.notNull(toolObjects, "toolObjects cannot be null");
+			Assert.noNullElements(toolObjects, "toolObjects cannot contain null elements");
+			this.functionCallbacks.addAll(Arrays.asList(ToolCallbacks.from(toolObjects)));
+			return this;
+		}
+
+		@Override
+		public ChatClientRequestSpec toolCallbacks(FunctionCallback... toolCallbacks) {
+			Assert.notNull(toolCallbacks, "toolCallbacks cannot be null");
+			Assert.noNullElements(toolCallbacks, "toolCallbacks cannot contain null elements");
+			this.functionCallbacks.addAll(Arrays.asList(toolCallbacks));
+			return this;
+		}
+
 		@Override
 		public <I, O> ChatClientRequestSpec function(String name, String description,
 				java.util.function.Function<I, O> function) {
@@ -888,10 +912,7 @@ public <I, O> ChatClientRequestSpec function(String name, String description, @N
 		}
 
 		public ChatClientRequestSpec functions(String... functionBeanNames) {
-			Assert.notNull(functionBeanNames, "functionBeanNames cannot be null");
-			Assert.noNullElements(functionBeanNames, "functionBeanNames cannot contain null elements");
-			this.functionNames.addAll(List.of(functionBeanNames));
-			return this;
+			return tools(functionBeanNames);
 		}
 
 		public ChatClientRequestSpec functions(FunctionCallback... functionCallbacks) {

spring-ai-core/src/main/java/org/springframework/ai/chat/client/DefaultChatClientBuilder.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.
@@ -30,10 +30,12 @@
 import org.springframework.ai.chat.client.DefaultChatClient.DefaultChatClientRequestSpec;
 import org.springframework.ai.chat.client.advisor.api.Advisor;
 import org.springframework.ai.chat.client.observation.ChatClientObservationConvention;
+import org.springframework.ai.chat.messages.Message;
 import org.springframework.ai.chat.model.ChatModel;
 import org.springframework.ai.chat.model.ToolContext;
 import org.springframework.ai.chat.prompt.ChatOptions;
 import org.springframework.ai.model.function.FunctionCallback;
+import org.springframework.ai.tool.ToolCallbacks;
 import org.springframework.core.io.Resource;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -147,6 +149,24 @@ public Builder defaultSystem(Consumer<PromptSystemSpec> systemSpecConsumer) {
 		return this;
 	}
 
+	@Override
+	public Builder defaultTools(String... toolNames) {
+		this.defaultRequest.functions(toolNames);
+		return this;
+	}
+
+	@Override
+	public Builder defaultTools(Object... toolObjects) {
+		this.defaultRequest.functions(ToolCallbacks.from(toolObjects));
+		return this;
+	}
+
+	@Override
+	public Builder defaultToolCallbacks(FunctionCallback... toolCallbacks) {
+		this.defaultRequest.functions(toolCallbacks);
+		return this;
+	}
+
 	public <I, O> Builder defaultFunction(String name, String description, java.util.function.Function<I, O> function) {
 		this.defaultRequest.function(name, description, function);
 		return this;
@@ -173,4 +193,17 @@ public Builder defaultToolContext(Map<String, Object> toolContext) {
 		return this;
 	}
 
+	void addMessages(List<Message> messages) {
+		this.defaultRequest.messages(messages);
+	}
+
+	void addToolCallbacks(List<FunctionCallback> toolCallbacks) {
+		Assert.notNull(toolCallbacks, "toolCallbacks cannot be null");
+		this.defaultRequest.toolCallbacks(toolCallbacks.toArray(FunctionCallback[]::new));
+	}
+
+	void addToolContext(Map<String, Object> toolContext) {
+		this.defaultRequest.toolContext(toolContext);
+	}
+
 }