Every Unix tool does four-and-a-half things:

- parse command line arguments in a slightly different way from other tools

- parse some ad hoc input format specific to itself

- do one or more actual jobs

- produce output in its own ad hoc format

- produces a termination status; here there can be variations: tools written "void main" that return a nondeterministic status; tools that use multiple nonzero codes for multiple interesting non-success conditions.

This messy way of doing things has "won" in AI ecosystems, I suppose.