Incorrect notification composed by template

Hello there! I wrote such simple template to send notifications over Telegram:

{{ define "helpdesk.alerts" }}
{{ .Status | toUpper }} on instance {{ .Labels.instance }}
{{.Annotations.summary}}
{{.Annotations.description}}
See details at {{ .DashboardURL }}
{{ end }}

This is the output supposed to be:

FIRING on instance instance1
Instance instance1 has been down for more than 5 minutes
(Blank description)
See details at https://grafana.loc/d/dashboard_uid?from=xxxxxx&orgId=xxxxx&to=xxxxxxx

But Telegram Bot I configured for alerts sends such notifications only:

FIRING on instance

Seems like template ignores variables. That happens both when I send test alert or Alert Manager sends real alerts. When I use pre-defied templates such as default.message and send a notification all variables are presented!

I think the problem is that your template is for a single rule but the template data is a group of alerts. Notification template reference | Grafana Cloud documentation