Can't access action.stdout in 'notify' scope

I'm trying to build action-chain workflow and I have a desire to use action.stdout within notify scope.
notify scope is the way to notify other systems (slack/hipchat) about action that just happened.
The thing is that apparently the variable is not accessible inside the notify scope, I just get {{some-variable}} name and not the variable content.

Example:

       -
        name: "check_down_endpoints"
        ref: "cassandra.check_down_endpoints"
        parameters:
            consul_servicename: '{{alert_body.commonLabels.servicename}}'
        on-failure: "fail_on_more_than_one_node"
        notify:
          on-success:
              routes:
                - hipchat
              message: "[StackStorm][SUCCESS] Workflow bla bla passed"
    -

        name: "Second-Action"
        ref: "core.remote_sudo"
        parameters:
            cmd: "<some command in here>"
            hosts: "{{check_down_endpoints.stdout.node}}"
            timeout: 1200
        on-success: "check"
        on-failure: "fail"
        notify:
          on-failure:
            routes:
              - hipchat
            message: "fail: {{action_parameters.hosts}}"
    -

When trying to get access to variable {{check_down_endpoints.stdout}} in here, I just get the variable name itself with brackets.

If this is meant to be it's really disappointing, there is a way to workaround that?
By the way didn't find what more action_context variables that is available - to those vars I can reach.
Also action_parameters are accessible so its good but still lack of information like stdout of other actions.

        notify:
          on-failure:
            routes:
              - hipchat
            message: "fail: {{check_down_endpoints.stdout}}"

message output in chat: "fail: {{check_down_endpoints.stdout}}"
Not the variable content as expected.