We define one word categories and their allocated budget in the "budget" tab, then the inbound text always takes the form of: "X.XX category as many words for description as you'd like."

As for doing this kind of thing with Twilio, here are the two building blocks you'd need:

Twilio + Python: https://www.twilio.com/docs/sms/quickstart/python

Python + Google Spreadsheets: https://www.twilio.com/blog/2017/02/an-easy-way-to-read-and-...