ontoolinput is not consistently called

[bgonzalez-thestable]

Describe the bug
Using the useApp hook, I notice app.ontoolinput is not consistently called although it is registered before app.connect

To Reproduce
Steps to reproduce the behavior:

1. Instantiate useApp() with a minimal setup:

import { useApp } from "@modelcontextprotocol/ext-apps/react";

//...

useApp({
  appInfo: { name: "Describe your app here...", version: "1.0.0" },
  capabilities: {},
  onAppCreated: (app) => {
    app.ontoolinput = (input) => {
      console.info("Received tool call input:", input);
    };
  },
});

2. Run the app in any host
3. Call a tool with user input using a manual prompt
4. Notice how app.ontoolinput is not always called

Expected behavior
app.ontoolinput is called every time a tool is invoked

Logs
If applicable, add logs to help explain your problem.

Additional context
Other callbacks seem to run as expected, including app.ontoolresult.