diff --git a/.changeset/eight-bananas-serve.md b/.changeset/eight-bananas-serve.md
new file mode 100644
index 0000000..e888f43
--- /dev/null
+++ b/.changeset/eight-bananas-serve.md
@@ -0,0 +1,5 @@
+---
+"@vercel/mcp-adapter": patch
+---
+
+Add more robust error handling to auth logic
diff --git a/src/next/auth-wrapper.ts b/src/next/auth-wrapper.ts
index 75e835d..307d24e 100644
--- a/src/next/auth-wrapper.ts
+++ b/src/next/auth-wrapper.ts
@@ -1,6 +1,13 @@
 import { AuthInfo } from "@modelcontextprotocol/sdk/server/auth/types";
+import { InvalidTokenError, InsufficientScopeError, ServerError } from "@modelcontextprotocol/sdk/server/auth/errors";
 import { withAuthContext } from "./auth-context";
 
+declare global {
+  interface Request {
+    auth?: AuthInfo;
+  }
+}
+
 export function withMcpAuth(
   handler: (req: Request) => Response | Promise<Response>,
   verifyToken: (
@@ -9,57 +16,92 @@ export function withMcpAuth(
   ) => AuthInfo | undefined | Promise<AuthInfo | undefined>,
   {
     required = false,
-    oauthResourcePath = "/.well-known/oauth-protected-resource",
+    resourceMetadataPath = "/.well-known/oauth-protected-resource",
+    requiredScopes,
   }: {
     required?: boolean;
-    oauthResourcePath?: string;
+    resourceMetadataPath?: string;
+    requiredScopes?: string[];
   } = {}
 ) {
   return async (req: Request) => {
-    const origin = new URL(req.url).origin;
+    try {
+      const authHeader = req.headers.get("Authorization");
+      const [type, token] = authHeader?.split(" ") || [];
 
-    const authHeader = req.headers.get("Authorization");
-    const [type, token] = authHeader?.split(" ") || [];
+      // Only support bearer token as per the MCP spec
+      // https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization#2-6-1-token-requirements
+      const bearerToken = type?.toLowerCase() === "bearer" ? token : undefined;
 
-    // Only support bearer token as per the MCP spec
-    // https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization#2-6-1-token-requirements
-    const bearerToken = type?.toLowerCase() === "bearer" ? token : undefined;
+      const authInfo = await verifyToken(req, bearerToken);
+      
+      if (required && !authInfo) {
+        throw new InvalidTokenError("No authorization provided");
+      }
 
-    const authInfo = await verifyToken(req, bearerToken);
+      if (!authInfo) {
+        return handler(req);
+      }
 
-    if (required && !authInfo) {
-      return new Response(
-        JSON.stringify({
-          error: "unauthorized_client",
-          error_description: "No authorization provided",
-        }),
-        {
-          status: 401,
-          headers: {
-            "WWW-Authenticate": `Bearer resource_metadata=${origin}${oauthResourcePath}`,
-          },
+      // Check if token has the required scopes (if any)
+      if (requiredScopes?.length) {
+        const hasAllScopes = requiredScopes.every(scope =>
+          authInfo.scopes.includes(scope)
+        );
+
+        if (!hasAllScopes) {
+          throw new InsufficientScopeError("Insufficient scope");
         }
-      );
-    }
+      }
 
-    if (!authInfo) {
-      return handler(req);
-    }
+      // Check if the token is expired
+      if (authInfo.expiresAt && authInfo.expiresAt < Date.now() / 1000) {
+        throw new InvalidTokenError("Token has expired");
+      }
+
+      // Set auth info on the request object after successful verification
+      req.auth = authInfo;
 
-    if (authInfo.expiresAt && authInfo.expiresAt < Date.now() / 1000) {
-      return new Response(
-        JSON.stringify({
-          error: "invalid_token",
-          error_description: "Authorization expired",
-        }),
-        {
+      return withAuthContext(authInfo, () => handler(req));
+    } catch (error) {
+      const origin = new URL(req.url).origin;
+      const resourceMetadataUrl = `${origin}${resourceMetadataPath}`;
+
+      if (error instanceof InvalidTokenError) {
+        return new Response(JSON.stringify(error.toResponseObject()), {
           status: 401,
           headers: {
-            "WWW-Authenticate": `Bearer error="invalid_token", error_description="Authorization expired", resource_metadata=${origin}${oauthResourcePath}`,
-          },
-        }
-      );
+            "WWW-Authenticate": `Bearer error="${error.errorCode}", error_description="${error.message}", resource_metadata="${resourceMetadataUrl}"`,
+            "Content-Type": "application/json"
+          }
+        });
+      } else if (error instanceof InsufficientScopeError) {
+        return new Response(JSON.stringify(error.toResponseObject()), {
+          status: 403,
+          headers: {
+            "WWW-Authenticate": `Bearer error="${error.errorCode}", error_description="${error.message}", resource_metadata="${resourceMetadataUrl}"`,
+            "Content-Type": "application/json"
+          }
+        });
+      } else if (error instanceof ServerError) {
+        return new Response(JSON.stringify(error.toResponseObject()), {
+          status: 500,
+          headers: {
+            "Content-Type": "application/json"
+          }
+        });
+      } else {
+        console.error("Unexpected error authenticating bearer token:", error);
+        const serverError = new ServerError("Internal Server Error");
+        return new Response(JSON.stringify(serverError.toResponseObject()), {
+          status: 500,
+          headers: {
+            "Content-Type": "application/json"
+          }
+        });
+      }
     }
-    return withAuthContext(authInfo, () => handler(req));
   };
 }
+
+
diff --git a/src/next/mcp-api-handler.ts b/src/next/mcp-api-handler.ts
index 0219073..f6976bb 100644
--- a/src/next/mcp-api-handler.ts
+++ b/src/next/mcp-api-handler.ts
@@ -322,7 +322,9 @@ export function initializeMcpApiHandler(
           url: req.url,
           headers: Object.fromEntries(req.headers),
           body: bodyContent,
+          auth: req.auth, // Use the auth info that should already be set by withMcpAuth
         });
+        
 
         // Create a response that will emit events
         const wrappedRes = new EventEmittingResponse(
@@ -666,7 +668,7 @@ interface FakeIncomingMessageOptions {
 // Create a fake IncomingMessage
 function createFakeIncomingMessage(
   options: FakeIncomingMessageOptions = {}
-): IncomingMessage {
+): IncomingMessage & { auth?: AuthInfo } {
   const {
     method = "GET",
     url = "/",
@@ -696,7 +698,7 @@ function createFakeIncomingMessage(
   }
 
   // Create the IncomingMessage instance
-  const req = new IncomingMessage(socket);
+  const req = new IncomingMessage(socket) as IncomingMessage & { auth?: AuthInfo };
 
   // Set the properties
   req.method = method;