Setting variables in the script (Help me plz)

Hello, I’m trying to set up a script but I’m getting an error

Message malformed: Entity {{ media_player_id }} is neither a valid entity ID nor a valid UUID for dictionary value @ data[‘entity_id’]

the essence of the script (briefly)
pass to the script: media player, volume and text
the script checks if the player is working or not
if not, sets the specified volume and plays the text, then returns the previous volume (already written, but the problem is in the wait_for_trigger block)
2nd part (not yet written) if the player was playing music, then pause, set the volume, play the text, return the volume of the music and resume it.

script below:

alias: Kodi (TTs)
mode: single
icon: mdi:kodi
fields:
  message:
    description: Что сказать?
    example: Привет мир!
  media_player_id:
    description: entity_id устройства
    example: media_player.kodi
  tts_volume:
    description: Громкость в %
    example: 90
variables:
  volume: |
    {{state_attr(media_player_id,"volume_level")}}
sequence:
  - if:
      - condition: template
        value_template: |
          {{states(media_player_id) == "idle"}}
    then:
      - service: media_player.volume_set
        data:
          volume_level: |
            {{ tts_volume / 100 }}
        target:
          entity_id: |
            {{ media_player_id }}
      - service: notify.notify
        data:
          message: |-
            Kodi бездействует, громкость {{ (volume * 100)|int }} %.
            Подготовка говорить, громкость {{ tts_volume }} %
      - service: tts.google_translate_say
        data:
          message: |
            {{ message }}
          cache: false
          language: ru
          entity_id: |
            {{ media_player_id }}
      - wait_for_trigger:
          - platform: state
            entity_id: "{{ media_player_id }}"
            from: playing
            to: idle
        timeout:
          hours: 0
          minutes: 0
          seconds: 20
          milliseconds: 0
      - service: media_player.volume_set
        data:
          volume_level: |
            {{ volume }}
        target:
          entity_id: |
            {{ media_player_id }}