Synthetic check annotations missing

I’ve set up simple http check with notification to slack. When site goes down all I receive to slack is:

[FIRING:1]  (SyntheticMonitoringCheckFailureAtHighSensitivity high https://grafana.com123123 test synthetic_monitoring)

how to include to message body descripton and summary? I tried to set up notification template but it doesn’t work.

on the other hand when I choose e-mail I get all information out of the box:

Labels
alertname = SyntheticMonitoringCheckFailureAtHighSensitivity
alert_sensitivity = high
instance = https://grafana.com123
job = test
namespace = synthetic_monitoring
Annotations
description = check job test instance https://grafana.com123 has a success rate of 0.0%.
summary = check success below 95%

so how to include that summaries to slack body message?