diff --git a/examples/simple-server/src/ui-react.tsx b/examples/simple-server/src/ui-react.tsx
index a8239e93..45275fff 100644
--- a/examples/simple-server/src/ui-react.tsx
+++ b/examples/simple-server/src/ui-react.tsx
@@ -37,7 +37,7 @@ export function McpClientApp() {
     try {
       const result = await app.callServerTool({
         name: "get-weather",
-        arguments: { city: "Tokyo" },
+        arguments: { location: "Tokyo" },
       });
       setMessages((prev) => [
         ...prev,
diff --git a/src/app-bridge.ts b/src/app-bridge.ts
index 90756a7a..c8d5345f 100644
--- a/src/app-bridge.ts
+++ b/src/app-bridge.ts
@@ -1,5 +1,5 @@
 import { Client } from "@modelcontextprotocol/sdk/client/index.js";
-import { ZodLiteral, ZodObject } from "zod";
+import { ZodLiteral, ZodObject } from "zod/v4";
 
 import { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
 import {
diff --git a/src/types.ts b/src/types.ts
index d58bfc5c..0ee4382c 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -7,7 +7,7 @@ import {
   RequestSchema,
   ToolSchema,
 } from "@modelcontextprotocol/sdk/types.js";
-import { z } from "zod";
+import { z } from "zod/v4";
 
 export const LATEST_PROTOCOL_VERSION = "2025-11-21";
 
@@ -77,7 +77,7 @@ export type McpUiSizeChangeNotification = z.infer<
 export const McpUiToolInputNotificationSchema = z.object({
   method: z.literal("ui/notifications/tool-input"),
   params: z.object({
-    arguments: z.record(z.unknown()).optional(),
+    arguments: z.record(z.string(), z.unknown()).optional(),
   }),
 });
 export type McpUiToolInputNotification = z.infer<
@@ -87,7 +87,7 @@ export type McpUiToolInputNotification = z.infer<
 export const McpUiToolInputPartialNotificationSchema = z.object({
   method: z.literal("ui/notifications/tool-input-partial"),
   params: z.object({
-    arguments: z.record(z.unknown()).optional(),
+    arguments: z.record(z.string(), z.unknown()).optional(),
   }),
 });
 export type McpUiToolInputPartialNotification = z.infer<