Park in the car park near the bridge over the Ruisseau de Rieu Claret stream on the Savoie side.
(S/E) From the car park, the start of the trail is not obvious, so the easiest way is to walk up the left bank of the stream (west-northwest), following the paths covered by runoff until you reach the waterfalls, where the trail becomes more marked.
Continue along this cairned trail to the IGN elevation of 2065m, where the Ruisseau du Pin (coming from the north) joins the Ruisseau du Buyant (coming from the west). Cross the Ruisseau du Pin at this point and follow the Ruisseau du Buyant along its left bank, following the natural paths that wind their way through scree and alpine grasslands, until you reach two large rocks at around 2250m, one of which is split.
(1) Then turn left (south) to go around the rounded rocks and approach the main bed of the Buyant stream. When you reach it, head due west (right) to go up it, following the numerous cairns. Pass under the Brèche du Lieutenant, then continue due west, climbing up large piles of boulders before reaching a marked plateau. A wide corridor opens onto this flat area.
Turn very slightly south (left) to climb this couloir up to the ridge, using the rocks on either side if necessary (useful in case of snow). The left side (i.e. right as you climb) of the couloir is the best choice, as the rock is more solid and easier, even if it seems steeper. As always, avoid the centre of the couloir.
(2) Once you reach the ridge, follow the ridge line first westwards and then south-westwards until you reach Pic de l'Agnelin, the highest point of the route.
(3) From the summit, a path descends the east face, never straying far from the south ridge of the peak. Follow this cairned path to Col de l'Agnelin.
(4) Leave your rucksack and walking poles at the pass and follow the ridge heading due south to an unnamed peak (2,714 m) offering superb views of the surrounding lakes and peaks. A few sections require you to use your hands on the rock, but the "climbing" rarely exceeds grade 3.
(5) At the summit, take the path northwards, which leads back to the Col de l'Agnelin.
(4). At the pass, look for the cairned path heading eastwards below and a small lake nestled in a corridor pointing towards the Brèche du Lieutenant. Follow this path to the lake.
(6) Just before reaching this small lake, turn right to follow a valley descending east-southeast towards Lac de l'Âne, which is clearly visible below. Go around Lac de l'Âne via one of its shores (the north shore is easier) to reach its spillway.
(7) At the spillway, take the left bank of the stream and head up the hillside to pass a slight ridge 200m to the south-east. From this ridge, the cairns marking the descent route are clearly visible, spaced 30 to 40m apart at most. Follow the faint path from cairn to cairn until you reach a much clearer trail after a short descent. This trail runs almost level at first to the east until it joins a trail heading south down the slope, beneath steep rocky foothills.
(8) At this junction, continue on the level path (to the left, towards the east) to climb up to a small pass about thirty metres higher. From this pass, take the path on the right which descends first to the east and then to the north-east. After passing the Sollier sheep park (dry stone walls), the path turns right at a right angle and descends along the right bank of the Rieu Claret stream to the main road running alongside Lake Grand'Maison.
On the road, turn left to cross the Rieu Claret bridge and reach the car park (S/E).

A very beautiful circular. Very few people venture as far as Agnelin.