Programs and data are the basis of deterministic results that are accessible to the llm.
Embedding an sqlite database with interesting information (bus schedules, dietary info, or a thousand other things) and a python program run by the skill can access it.
For Claude at least, it does it in a VM and can be used from your phone.
Sure, skills are more convention than a standard right now. Skills lack versioning, distribution, updates, unique naming, selective network access. But they are incredibly useful and accessible.