Did you verify this is a real problem by searching the NativeScript Forum and the [other open issues in this repo]

I've confirmed it myself:
(https://github.com/NativeScript/nativescript/issues)?

Tell us about the problem

TalkBack on Android reads Navigation buttons on the ActionBar as just "Button" without any label.

Which platform(s) does your issue occur on?

Android only.

Please provide the following version numbers that your issue occurs with:

• CLI: (run tns --version to fetch it)
• Cross-platform modules: 4.1.0
• Runtime(s): android 4.1.2
• Plugin(s): none

Please tell us how to recreate the issue in as much detail as possible.

Demo project link below.
Navigate to any item and notice the "<-" button, this button should be read as "Back button" by TalkBack, but is only read as "Button".

You can see the screenshot from uiautomationviewer above, content-desc should have the value "Back" but have none.

Is there code involved? If so, please share the minimal amount of code needed to recreate the problem.

https://github.com/m-abs/ns-debugging/tree/master/missing-nav-content-desc

Note: I'll submit a PR fixing this