Add Support for Jackson 3 and use it by default

mcp-core/pom.xml

@@ -80,7 +80,7 @@
 		<dependency>
 			<groupId>com.fasterxml.jackson.core</groupId>
 			<artifactId>jackson-annotations</artifactId>
-			<version>${jackson.version}</version>
+			<version>${jackson-annotations.version}</version>
 		</dependency>
 
 		<dependency>
@@ -100,7 +100,7 @@
 		<!-- Test dependencies -->
         <dependency>
             <groupId>io.modelcontextprotocol.sdk</groupId>
-            <artifactId>mcp-json-jackson2</artifactId>
+            <artifactId>mcp-json-jackson3</artifactId>
             <version>0.18.0-SNAPSHOT</version>
             <scope>test</scope>
         </dependency>

mcp-core/src/test/java/io/modelcontextprotocol/spec/McpSchemaTests.java

@@ -18,7 +18,7 @@
 
 import org.junit.jupiter.api.Test;
 
-import com.fasterxml.jackson.databind.exc.InvalidTypeIdException;
+import tools.jackson.databind.exc.InvalidTypeIdException;
 
 import io.modelcontextprotocol.spec.McpSchema.TextResourceContents;
 import net.javacrumbs.jsonunit.core.Option;

mcp-json-jackson2/pom.xml

@@ -11,7 +11,7 @@
 	<artifactId>mcp-json-jackson2</artifactId>
 	<packaging>jar</packaging>
 	<name>Java MCP SDK JSON Jackson</name>
-	<description>Java MCP SDK JSON implementation based on Jackson</description>
+	<description>Java MCP SDK JSON implementation based on Jackson 2</description>
 	<url>https://github.com/modelcontextprotocol/java-sdk</url>
 	<scm>
 		<url>https://github.com/modelcontextprotocol/java-sdk</url>
@@ -42,12 +42,12 @@
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
-            <version>${jackson.version}</version>
+            <version>${jackson2.version}</version>
         </dependency>
         <dependency>
             <groupId>com.networknt</groupId>
             <artifactId>json-schema-validator</artifactId>
-            <version>${json-schema-validator.version}</version>
+            <version>${json-schema-validator-jackson2.version}</version>
         </dependency>
 
 		<dependency>

mcp-json-jackson3/pom.xml

@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>io.modelcontextprotocol.sdk</groupId>
+		<artifactId>mcp-parent</artifactId>
+		<version>0.18.0-SNAPSHOT</version>
+	</parent>
+	<artifactId>mcp-json-jackson3</artifactId>
+	<packaging>jar</packaging>
+	<name>Java MCP SDK JSON Jackson</name>
+	<description>Java MCP SDK JSON implementation based on Jackson 3</description>
+	<url>https://github.com/modelcontextprotocol/java-sdk</url>
+	<scm>
+		<url>https://github.com/modelcontextprotocol/java-sdk</url>
+		<connection>git://github.com/modelcontextprotocol/java-sdk.git</connection>
+		<developerConnection>git@github.com/modelcontextprotocol/java-sdk.git</developerConnection>
+	</scm>
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-jar-plugin</artifactId>
+				<configuration>
+					<archive>
+                        <manifest>
+                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
+                        </manifest>
+					</archive>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+	<dependencies>
+        <dependency>
+            <groupId>io.modelcontextprotocol.sdk</groupId>
+            <artifactId>mcp-json</artifactId>
+            <version>0.18.0-SNAPSHOT</version>
+        </dependency>
+        <dependency>
+            <groupId>tools.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.networknt</groupId>
+            <artifactId>json-schema-validator</artifactId>
+            <version>${json-schema-validator-jackson3.version}</version>
+        </dependency>
+
+		<dependency>
+			<groupId>org.assertj</groupId>
+			<artifactId>assertj-core</artifactId>
+			<version>${assert4j.version}</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter-api</artifactId>
+			<version>${junit.version}</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter-params</artifactId>
+			<version>${junit.version}</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.mockito</groupId>
+			<artifactId>mockito-core</artifactId>
+			<version>${mockito.version}</version>
+			<scope>test</scope>
+		</dependency>
+
+	</dependencies>
+</project>

mcp-json-jackson3/src/main/java/io/modelcontextprotocol/json/jackson3/JacksonMcpJsonMapper.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2026 - 2026 the original author or authors.
+ */
+
+package io.modelcontextprotocol.json.jackson3;
+
+import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.TypeRef;
+
+import tools.jackson.databind.JavaType;
+import tools.jackson.databind.json.JsonMapper;
+
+/**
+ * Jackson-based implementation of JsonMapper. Wraps a Jackson JsonMapper but keeps the
+ * SDK decoupled from Jackson at the API level.
+ */
+public final class JacksonMcpJsonMapper implements McpJsonMapper {
+
+	private final JsonMapper jsonMapper;
+
+	/**
+	 * Constructs a new JacksonMcpJsonMapper instance with the given JsonMapper.
+	 * @param jsonMapper the JsonMapper to be used for JSON serialization and
+	 * deserialization. Must not be null.
+	 * @throws IllegalArgumentException if the provided JsonMapper is null.
+	 */
+	public JacksonMcpJsonMapper(JsonMapper jsonMapper) {
+		if (jsonMapper == null) {
+			throw new IllegalArgumentException("JsonMapper must not be null");
+		}
+		this.jsonMapper = jsonMapper;
+	}
+
+	/**
+	 * Returns the underlying Jackson {@link JsonMapper} used for JSON serialization and
+	 * deserialization.
+	 * @return the JsonMapper instance
+	 */
+	public JsonMapper getJsonMapper() {
+		return jsonMapper;
+	}
+
+	@Override
+	public <T> T readValue(String content, Class<T> type) {
+		return jsonMapper.readValue(content, type);
+	}
+
+	@Override
+	public <T> T readValue(byte[] content, Class<T> type) {
+		return jsonMapper.readValue(content, type);
+	}
+
+	@Override
+	public <T> T readValue(String content, TypeRef<T> type) {
+		JavaType javaType = jsonMapper.getTypeFactory().constructType(type.getType());
+		return jsonMapper.readValue(content, javaType);
+	}
+
+	@Override
+	public <T> T readValue(byte[] content, TypeRef<T> type) {
+		JavaType javaType = jsonMapper.getTypeFactory().constructType(type.getType());
+		return jsonMapper.readValue(content, javaType);
+	}
+
+	@Override
+	public <T> T convertValue(Object fromValue, Class<T> type) {
+		return jsonMapper.convertValue(fromValue, type);
+	}
+
+	@Override
+	public <T> T convertValue(Object fromValue, TypeRef<T> type) {
+		JavaType javaType = jsonMapper.getTypeFactory().constructType(type.getType());
+		return jsonMapper.convertValue(fromValue, javaType);
+	}
+
+	@Override
+	public String writeValueAsString(Object value) {
+		return jsonMapper.writeValueAsString(value);
+	}
+
+	@Override
+	public byte[] writeValueAsBytes(Object value) {
+		return jsonMapper.writeValueAsBytes(value);
+	}
+
+}

mcp-json-jackson3/src/main/java/io/modelcontextprotocol/json/jackson3/JacksonMcpJsonMapperSupplier.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2026 - 2026 the original author or authors.
+ */
+
+package io.modelcontextprotocol.json.jackson3;
+
+import tools.jackson.databind.json.JsonMapper;
+
+import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.McpJsonMapperSupplier;
+
+/**
+ * A supplier of {@link McpJsonMapper} instances that uses the Jackson library for JSON
+ * serialization and deserialization.
+ * <p>
+ * This implementation provides a {@link McpJsonMapper} backed by a Jackson
+ * {@link JsonMapper}.
+ */
+public class JacksonMcpJsonMapperSupplier implements McpJsonMapperSupplier {
+
+	/**
+	 * Returns a new instance of {@link McpJsonMapper} that uses the Jackson library for
+	 * JSON serialization and deserialization.
+	 * <p>
+	 * The returned {@link McpJsonMapper} is backed by a new instance of
+	 * {@link tools.jackson.databind.json.JsonMapper}.
+	 * @return a new {@link McpJsonMapper} instance
+	 */
+	@Override
+	public McpJsonMapper get() {
+		return new JacksonMcpJsonMapper(JsonMapper.shared());
+	}
+
+}