This simple script will get the number of unread messages in the label

https://github.com/jpierrevilleres/browser-samples/tree/master/gmail/quickstart

https://developers.google.com/gmail/api/quickstart/python

https://developers.google.com/api-client-library/python

Gmail API Browser Quickstart

Complete the steps described in the quickstart instructions, and in about five minutes you’ll have a simple browser application that makes requests to the Gmail API.

Run

After following the quickstart instructions, run the sample:

python -m SimpleHTTPServer 8000

And opening the web page:

open http://localhost:8000

 

https://developers.google.com/gmail/api/v1/reference/users/labels

https://developers.google.com/gmail/api/v1/reference/users/labels#methods

 

messagesUnread

integer

The number of unread messages with the label.