Use helper value with notify.google_assistant_sdk

I’m trying to use a helper to broadcast to the right room. This is what i wrote:

service: notify.google_assistant_sdk
data:
  message: This is a test
  target:  " {{input_text.ignacio_s_room_presence }} "

Alas, it is giving me the following error:

Failed to call service notify.google_assistant_sdk. Error rendering data template: UndefinedError: 'input_text' is undefined

What am I doing wrong?