diff --git a/package-lock.json b/package-lock.json
index 9dd8236b..016adf94 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,5 +1,6 @@
 {
   "name": "@modelcontextprotocol/sdk",
+  "version": "1.13.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
diff --git a/src/server/sse.ts b/src/server/sse.ts
index 06c0bc8d..a54e5788 100644
--- a/src/server/sse.ts
+++ b/src/server/sse.ts
@@ -20,7 +20,7 @@ export class SSEServerTransport implements Transport {
   private _sessionId: string;
   onclose?: () => void;
   onerror?: (error: Error) => void;
-  onmessage?: (message: JSONRPCMessage, extra: { authInfo?: AuthInfo, requestInfo: RequestInfo }) => void;
+  onmessage?: (message: JSONRPCMessage, extra?: MessageExtraInfo) => void;
 
   /**
    * Creates a new SSE server transport, which will direct the client to POST messages to the relative or absolute URL identified by `_endpoint`.
@@ -119,7 +119,7 @@ export class SSEServerTransport implements Transport {
   /**
    * Handle a client message, regardless of how it arrived. This can be used to inform the server of messages that arrive via a means different than HTTP POST.
    */
-  async handleMessage(message: unknown, extra: MessageExtraInfo): Promise<void> {
+  async handleMessage(message: unknown, extra?: MessageExtraInfo): Promise<void> {
     let parsedMessage: JSONRPCMessage;
     try {
       parsedMessage = JSONRPCMessageSchema.parse(message);
diff --git a/src/server/streamableHttp.ts b/src/server/streamableHttp.ts
index b5f8aca7..807743eb 100644
--- a/src/server/streamableHttp.ts
+++ b/src/server/streamableHttp.ts
@@ -114,7 +114,7 @@ export class StreamableHTTPServerTransport implements Transport {
   sessionId?: string;
   onclose?: () => void;
   onerror?: (error: Error) => void;
-  onmessage?: (message: JSONRPCMessage, extra: MessageExtraInfo) => void;
+  onmessage?: (message: JSONRPCMessage, extra?: MessageExtraInfo) => void;
 
   constructor(options: StreamableHTTPServerTransportOptions) {
     this.sessionIdGenerator = options.sessionIdGenerator;
diff --git a/src/server/types/types.ts b/src/server/types/types.ts
index 1114e50b..3892af6c 100644
--- a/src/server/types/types.ts
+++ b/src/server/types/types.ts
@@ -22,7 +22,7 @@ export interface MessageExtraInfo {
   /**
    * The request information.
    */
-  requestInfo: RequestInfo;
+  requestInfo?: RequestInfo;
 
   /**
    * The authentication information.
diff --git a/src/shared/protocol.ts b/src/shared/protocol.ts
index ae539c17..33afd70e 100644
--- a/src/shared/protocol.ts
+++ b/src/shared/protocol.ts
@@ -131,7 +131,7 @@ export type RequestHandlerExtra<SendRequestT extends Request,
     /**
      * The original HTTP request.
      */
-    requestInfo: RequestInfo;
+    requestInfo?: RequestInfo;
 
     /**
      * Sends a notification that relates to the current request being handled.
@@ -345,7 +345,7 @@ export abstract class Protocol<
       );
   }
 
-  private _onrequest(request: JSONRPCRequest, extra: MessageExtraInfo): void {
+  private _onrequest(request: JSONRPCRequest, extra?: MessageExtraInfo): void {
     const handler =
       this._requestHandlers.get(request.method) ?? this.fallbackRequestHandler;
 
@@ -381,7 +381,7 @@ export abstract class Protocol<
         this.request(r, resultSchema, { ...options, relatedRequestId: request.id }),
       authInfo: extra?.authInfo,
       requestId: request.id,
-      requestInfo: extra.requestInfo
+      requestInfo: extra?.requestInfo
     };
 
     // Starting with Promise.resolve() puts any synchronous errors into the monad as well.
diff --git a/src/shared/transport.ts b/src/shared/transport.ts
index 60434a68..69fce10e 100644
--- a/src/shared/transport.ts
+++ b/src/shared/transport.ts
@@ -70,7 +70,7 @@ export interface Transport {
    * 
    * The requestInfo can be used to get the original request information (headers, etc.)
    */
-  onmessage?: (message: JSONRPCMessage, extra: MessageExtraInfo) => void;
+  onmessage?: (message: JSONRPCMessage, extra?: MessageExtraInfo) => void;
 
   /**
    * The session ID generated for this connection.