The medallion has 3 charges. While wearing it, you can use an action and expend 1 charge to cast the detect thoughts spell (save DC 13) from it. The medallion regains 1d3 expended charges daily at dawn.
Medallion of Thoughts in the 2024 rules
The 2024 Dungeon Master’s Guide revised the magic items, and the SRD 5.2 carries the new text. What changed:
Dice: 1d3 → 1d4.
Type
Wondrous Item
Rarity
Uncommon
Attunement
Required
The medallion has 5 charges. While wearing it, you can expend 1 charge to cast Detect Thoughts (save DC 13) from it. The medallion regains 1d4 expended charges daily at dawn.