Help with understanding scripts \ how to call a script from an automation

At the present time I have lots of automations which make my Amazon Echo’s speak or carry out actions.

Its a little repetitive and I’m thinking that there must be a way to create some sort of a script that I can pass the “message” to.

The automations usually look like this:

service: notify.alexa_media_Everywhere
data:
  message: System Armed
  data:
    type: announce
    method: all

I did look at the documentation and it looks like I just need to change it to be like this??

service: notify.alexa_media_Everywhere
data:
  message: {{ Message_String }}
data:
    type: announce
    method: all

If thats right can someone let me know. And then there’s the question of “how to call the script”
If someone could point me in the right direction would appreciate it.