To help find metrics in the [Glean Dictionary] and other tools, metrics should contain tag metadata corresponding to the
feature area(s) that they belong to. In the case of Firefox for Android, tag information is based off of the GitHub feature labels for this repository:
information directly when adding or modifying `metrics.yaml`. Just add a section called `metadata` to the metric and add a list of tags that correspond to it.
If a feature labels is ever added or removed, you can synchronize the tags file in the source tree by running `./tools/update-glean-tags.py` in the root of the repository.
Note that a tag *must* be specified in `tags.yaml` for it to be usable in a metric, so if a tag is removed from `tags.yaml` all uses of it must be removed from `metrics.yaml`.