Because both of these are currently invalid syntax, it’s possible for tag strings to additionally both support dotted names:
lazy.f"Like f-string, but this tag function lazily evaluates {expr}"
and atomic expressions
(resolve_to_tag_function())"The velocity of an unladen sparrow is {velocity} m/s"
I can see arguments either way (shorter names vs avoid namespace cluttering). In practice, it is somewhat more involved/difficult to implement these two additional cases, but if the ergonomics make sense to the community, that’s likely a reasonable cost.