Guidelines for technical documentation of applications/integrations?

Hi guys

As a Project Manager, I often ask developers to "document" or "describe" the application/integration we are about to build in technical terms.

Our company doesn't have a strong documentation-culture, and people usually just duck right in.

I'm missing some guidelines on what areas I might use as a baseline for describing applications/integrations.

These are some of the things I would like to be described before writing a single line of code:

• A written description of the component ("What does it do?") in human language
• Interfaces:
  • Where are we getting data from?
  • Where are we outputting data to?
  • What formats do we work with?
• Mappings:
  • Requirements for incoming data
  • Requirements for outgoing data

What other "generic" documentation areas would I be able to include?