diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/DefaultSseMessageEndpointValidator.java b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/DefaultSseMessageEndpointValidator.java
index 4be5875db..b50a9c7ba 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/DefaultSseMessageEndpointValidator.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/DefaultSseMessageEndpointValidator.java
@@ -14,7 +14,10 @@
  * SSE uri, or be a relative uri.
  *
  * @author Daniel Garnier-Moiroux
+ * @deprecated This validator is part of the deprecated SSE transport.
+ * @see HttpClientSseClientTransport
  */
+@Deprecated
 public final class DefaultSseMessageEndpointValidator implements SseMessageEndpointValidator {
 
 	@Override
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
index 050c7dd9a..874da905e 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
@@ -62,9 +62,15 @@
  * </ul>
  *
  * @author Christian Tzolov
+ * @deprecated This SSE transport is deprecated. Use Streamable HTTP instead, with
+ * {@link HttpClientStreamableHttpTransport}.
  * @see io.modelcontextprotocol.spec.McpTransport
  * @see io.modelcontextprotocol.spec.McpClientTransport
+ * @see <a href=
+ * "https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#backwards-compatibility">Transports
+ * backwards compatibility</a>
  */
+@Deprecated
 public class HttpClientSseClientTransport implements McpClientTransport {
 
 	private static final String MCP_PROTOCOL_VERSION = ProtocolVersions.MCP_2024_11_05;
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/InvalidSseMessageEndpointException.java b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/InvalidSseMessageEndpointException.java
index 6acdfae51..6bbbd1b18 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/InvalidSseMessageEndpointException.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/InvalidSseMessageEndpointException.java
@@ -9,7 +9,10 @@
  * not valid.
  *
  * @author Daniel Garnier-Moiroux
+ * @deprecated This exception is part of the deprecated SSE transport.
+ * @see HttpClientSseClientTransport
  */
+@Deprecated
 public class InvalidSseMessageEndpointException extends Exception {
 
 	private final String messageEndpoint;
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/SseMessageEndpointValidator.java b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/SseMessageEndpointValidator.java
index 322e64638..990e76e6b 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/SseMessageEndpointValidator.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/client/transport/SseMessageEndpointValidator.java
@@ -11,7 +11,10 @@
  * {@link InvalidSseMessageEndpointException} when then endpoint is not valid.
  *
  * @author Daniel Garnier-Moiroux
+ * @deprecated This validator is part of the deprecated SSE transport.
+ * @see HttpClientSseClientTransport
  */
+@Deprecated
 @FunctionalInterface
 public interface SseMessageEndpointValidator {
 
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java
index 0fb2fa778..69d73f7ab 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java
@@ -62,11 +62,17 @@
  * </ul>
  *
  * @author Christian Tzolov
+ * @deprecated This SSE transport is deprecated. Use Streamable HTTP instead, with
+ * {@link HttpServletStreamableServerTransportProvider} or
+ * {@link HttpServletStatelessServerTransport}.
  * @author Alexandros Pappas
  * @see McpServerTransportProvider
  * @see HttpServlet
+ * @see <a href=
+ * "https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#backwards-compatibility">Transports
+ * backwards compatibility</a>
  */
-
+@Deprecated
 @WebServlet(asyncSupported = true)
 public class HttpServletSseServerTransportProvider extends HttpServlet implements McpServerTransportProvider {