Proposal: Stream Tool Arguments

[MiguelsPizza]

Currently, execute fires after the full args JSON is parsed. For tools with large text args (email bodies, code), it'd be nice to stream chunks into page UI as the model generates them. example from userland

navigator.modelContext.registerTool({
  name: "compose_email",
  stream: true,
  inputSchema: { /* to, subject, body */ },
  execute: async (call) => {
    composer.open();
    for await (const { key, chunk } of call) {
      if (key === "to")   composer.appendTo(chunk);
      if (key === "body") composer.appendBody(chunk);
    }
    const { to, subject, body } = await call.args;
    return { content: [{ type: "text", text: `Draft created` }] };
  }
});

For declarative tools this could be default behavior.