Worth reminding everyone of the clarification
Key points
It is the trail that is important - so the description should focus on the trail.
Why is it good to follow this route eg what you might see or interact with.
There is no set distance requirement.
Markers by design are meant to look the same and may be mass produced - not a reason to reject.
But the marker should be fulfilling a function as an anchor for the trail - most commonly it’s at a decision point to help you stay on the correct path to follow the route.
The marker should be linkable to the trail - a name/number/symbol for example that show it is relevant to that trail
A direction sign lacks those links because it is not an anchor for a trail.
Unfortunately some reviewers still seem to focus on the sign rather than the trail.