Tracking containment alerts: document fields in notification mail body

I set up a rule to send an email when a document contains a location (Point) that is contained in a specific area.
The rules triggers correctly the alert, but I haven't been able to add to the mail body field from the document.
The document is a json of this kind

  "_index": "index-2022.07.19",
  "_id": "2W1OFoIBvTe4_JXgv2Mc",
  "_version": 1,
  "_score": null,
  "fields": {
    "location": [
        "coordinates": [
        "type": "Point"
    "myLocation": [

I've tried the following notations:

item with id {{_source.myIDField}} entered the area at {{_source.myLocation}} 


item with id {{context.hits.0.myIDField}} entered the area at {{context.hits.0.myLocation}}

Any suggestion on how to read those field?

Thanks for any help you could provide,

are you using watcher or alerting?

Kibana Alerting