chore(js/plugins/mcp): fixes to README.md (#2778)

Author: pavelgj

js/plugins/mcp/README.md

@@ -94,11 +94,12 @@ ai.defineTool(
 
 ai.definePrompt(
   {
-    name: 'happy',
-    description: 'everybody together now',
+    name: "happy",
+    description: "everybody together now",
     input: {
-      schema: z.object({ action: z.string().optional() }),
-      default: { action: 'clap your hands' },
+      schema: z.object({
+        action: z.string().default("clap your hands").optional(),
+      }),
     },
   },
   `If you're happy and you know it, {{action}}.`