How to document metrics output from an application?

We have a number of applications, each with a medium-sized set of metrics being outputted.
Some metrics are common to all applications, like ‘uptime’, while most metrics are custom.

We have found it difficult to maintain a good way of documenting what outputs each application generates so the docs can be used in the other end of the chain, by the people setting up the monitoring tools.

Does anyone know of good examples of how to document metrics output? Are there tools for generating this into structured documentation.

I managed to find a very neat example of metrics documentation here: InfluxDB metrics | Vector documentation but it is not clear where this documentation is generated from and trying to dig into it, the setup feels very complex. I was hoping for something simpler to start with.