FunctionToolCallback support output schema

mcp/common/src/main/java/org/springframework/ai/mcp/McpToolUtils.java

@@ -24,9 +24,11 @@
 
 import com.fasterxml.jackson.annotation.JsonAlias;
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import io.micrometer.common.util.StringUtils;
 import io.modelcontextprotocol.client.McpAsyncClient;
 import io.modelcontextprotocol.client.McpSyncClient;
+import io.modelcontextprotocol.json.jackson.JacksonMcpJsonMapper;
 import io.modelcontextprotocol.server.McpServerFeatures;
 import io.modelcontextprotocol.server.McpStatelessServerFeatures;
 import io.modelcontextprotocol.server.McpSyncServerExchange;
@@ -74,6 +76,8 @@ public final class McpToolUtils {
 	 */
 	public static final String TOOL_CONTEXT_MCP_EXCHANGE_KEY = "exchange";
 
+	private static final JacksonMcpJsonMapper objectMapper = new JacksonMcpJsonMapper(new ObjectMapper());
+
 	private McpToolUtils() {
 	}
 
@@ -253,6 +257,7 @@ private static SharedSyncToolSpecification toSharedSyncToolSpecification(ToolCal
 			.description(toolCallback.getToolDefinition().description())
 			.inputSchema(ModelOptionsUtils.jsonToObject(toolCallback.getToolDefinition().inputSchema(),
 					McpSchema.JsonSchema.class))
+			.outputSchema(objectMapper, toolCallback.getToolDefinition().outputSchema())
 			.build();
 
 		return new SharedSyncToolSpecification(tool, (exchangeOrContext, request) -> {

spring-ai-model/src/main/java/org/springframework/ai/tool/definition/DefaultToolDefinition.java

@@ -26,7 +26,8 @@
  * @author Thomas Vitale
  * @since 1.0.0
  */
-public record DefaultToolDefinition(String name, String description, String inputSchema) implements ToolDefinition {
+public record DefaultToolDefinition(String name, String description, String inputSchema,
+		String outputSchema) implements ToolDefinition {
 
 	public DefaultToolDefinition {
 		Assert.hasText(name, "name cannot be null or empty");
@@ -46,6 +47,8 @@ public static final class Builder {
 
 		private String inputSchema;
 
+		private String outputSchema;
+
 		private Builder() {
 		}
 
@@ -64,12 +67,17 @@ public Builder inputSchema(String inputSchema) {
 			return this;
 		}
 
+		public Builder outputSchema(String outputSchema) {
+			this.outputSchema = outputSchema;
+			return this;
+		}
+
 		public ToolDefinition build() {
 			if (!StringUtils.hasText(this.description)) {
 				Assert.hasText(this.name, "toolName cannot be null or empty");
 				this.description = ParsingUtils.reConcatenateCamelCase(this.name, " ");
 			}
-			return new DefaultToolDefinition(this.name, this.description, this.inputSchema);
+			return new DefaultToolDefinition(this.name, this.description, this.inputSchema, this.outputSchema);
 		}
 
 	}

spring-ai-model/src/main/java/org/springframework/ai/tool/definition/ToolDefinition.java

@@ -39,6 +39,8 @@ public interface ToolDefinition {
 	 */
 	String inputSchema();
 
+	String outputSchema();
+
 	/**
 	 * Create a default {@link ToolDefinition} builder.
 	 */

spring-ai-model/src/main/java/org/springframework/ai/tool/function/FunctionToolCallback.java

@@ -172,6 +172,10 @@ public static final class Builder<I, O> {
 
 		private Type inputType;
 
+		private String outputSchema;
+
+		private Type outputType;
+
 		private ToolMetadata toolMetadata;
 
 		private BiFunction<I, ToolContext, O> toolFunction;
@@ -206,6 +210,16 @@ public Builder<I, O> inputType(ParameterizedTypeReference<?> inputType) {
 			return this;
 		}
 
+		public Builder<I, O> outputSchema(String outputSchema) {
+			this.outputSchema = outputSchema;
+			return this;
+		}
+
+		public Builder<I, O> outputType(Type outputType) {
+			this.outputType = outputType;
+			return this;
+		}
+
 		public Builder<I, O> toolMetadata(ToolMetadata toolMetadata) {
 			this.toolMetadata = toolMetadata;
 			return this;
@@ -224,6 +238,8 @@ public FunctionToolCallback<I, O> build() {
 						: ToolUtils.getToolDescriptionFromName(this.name))
 				.inputSchema(StringUtils.hasText(this.inputSchema) ? this.inputSchema
 						: JsonSchemaGenerator.generateForType(this.inputType))
+				.outputSchema(StringUtils.hasText(this.outputSchema) ? this.outputSchema
+						: JsonSchemaGenerator.generateForType(this.outputType))
 				.build();
 			return new FunctionToolCallback<>(toolDefinition, this.toolMetadata, this.inputType, this.toolFunction,
 					this.toolCallResultConverter);

spring-ai-model/src/test/java/org/springframework/ai/tool/execution/DefaultToolExecutionExceptionProcessorTests.java

@@ -40,7 +40,7 @@ class DefaultToolExecutionExceptionProcessorTests {
 	private final Error toolError = new Error("Error");
 
 	private final DefaultToolDefinition toolDefinition = new DefaultToolDefinition("toolName", "toolDescription",
-			"inputSchema");
+			"inputSchema", "outputSchema");
 
 	private final ToolExecutionException toolExecutionException = new ToolExecutionException(this.toolDefinition,
 			this.toolException);