How to describe a generic interface?

Question

User interface

Hello!
There is an application (server) built on modules. Each module must provide the client with a description of the interface so that the client downloads the file and draws what it needs. (Initially, it is impossible to score the interface to the client, since the modules are dynamic and can appear at any time).
Clients are also different (android, web, desktop), which means that the technologies for writing the interface are different.
What is the best way to describe an interface universally?
How to use XML or Json as a description?

Answer 1

JSON