The crux of this route is the junkly slot used at the bottom to access the main climb. If this is skipped, the route might be 5.2 or 5.3.
Climb up the slot and to a sizable pine tree, then head up a brief near-vertical section of South face to pull up onto the SE ridge. The South end of the East Face improves in quality from here and goes up to a main summit, and then it goes to a slightly smaller summit westward still.
Scramble off of the top and return to the base around the South end of the rock.
This route starts up the obvious slot low and left (South) on the East Face of the West Sentinel, perhaps 2 meters off of the Royal Arch trail, 5-10 meters downhill (South) from Sentinel Pass.
If you wish to skip the crux and the iffy rock, hike South around the lowest part of the rock and back up and West to the pine tree above the slot, and pull onto the Southeast Ridge from there via jugs on a 10' off-vertical wall.
There is not much protection to be had, as per usual on the Flatirons. We simply soloed it.