diff --git a/src/client/auth.test.ts b/src/client/auth.test.ts
index cc4717ec..629feab7 100644
--- a/src/client/auth.test.ts
+++ b/src/client/auth.test.ts
@@ -39,7 +39,7 @@ describe("OAuth Authorization", () => {
       const [url, options] = calls[0];
       expect(url.toString()).toBe("https://auth.example.com/.well-known/oauth-authorization-server");
       expect(options.headers).toEqual({
-        "MCP-Protocol-Version": "2024-11-05"
+        "MCP-Protocol-Version": "2025-03-26"
       });
     });
 
@@ -478,4 +478,4 @@ describe("OAuth Authorization", () => {
       ).rejects.toThrow("Dynamic client registration failed");
     });
   });
-});
\ No newline at end of file
+});
diff --git a/src/types.ts b/src/types.ts
index 17b485f8..a2b906e5 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,8 +1,9 @@
 import { z, ZodTypeAny } from "zod";
 
-export const LATEST_PROTOCOL_VERSION = "2024-11-05";
+export const LATEST_PROTOCOL_VERSION = "2025-03-26";
 export const SUPPORTED_PROTOCOL_VERSIONS = [
   LATEST_PROTOCOL_VERSION,
+  "2024-11-05",
   "2024-10-07",
 ];
 
@@ -754,11 +755,11 @@ export const PromptListChangedNotificationSchema = NotificationSchema.extend({
 /* Tools */
 /**
  * Additional properties describing a Tool to clients.
- * 
- * NOTE: all properties in ToolAnnotations are **hints**. 
- * They are not guaranteed to provide a faithful description of 
+ *
+ * NOTE: all properties in ToolAnnotations are **hints**.
+ * They are not guaranteed to provide a faithful description of
  * tool behavior (including descriptive properties like `title`).
- * 
+ *
  * Clients should never make tool use decisions based on ToolAnnotations
  * received from untrusted servers.
  */
@@ -771,7 +772,7 @@ export const ToolAnnotationsSchema = z
 
     /**
      * If true, the tool does not modify its environment.
-     * 
+     *
      * Default: false
      */
     readOnlyHint: z.optional(z.boolean()),
@@ -779,19 +780,19 @@ export const ToolAnnotationsSchema = z
     /**
      * If true, the tool may perform destructive updates to its environment.
      * If false, the tool performs only additive updates.
-     * 
+     *
      * (This property is meaningful only when `readOnlyHint == false`)
-     * 
+     *
      * Default: true
      */
     destructiveHint: z.optional(z.boolean()),
 
     /**
-     * If true, calling the tool repeatedly with the same arguments 
+     * If true, calling the tool repeatedly with the same arguments
      * will have no additional effect on the its environment.
-     * 
+     *
      * (This property is meaningful only when `readOnlyHint == false`)
-     * 
+     *
      * Default: false
      */
     idempotentHint: z.optional(z.boolean()),
@@ -801,7 +802,7 @@ export const ToolAnnotationsSchema = z
      * entities. If false, the tool's domain of interaction is closed.
      * For example, the world of a web search tool is open, whereas that
      * of a memory tool is not.
-     * 
+     *
      * Default: true
      */
     openWorldHint: z.optional(z.boolean()),