diff --git a/mods/HUD/mcl_formspec/API.md b/mods/HUD/mcl_formspec/API.md
index e69de29bb..64795f8c3 100644
--- a/mods/HUD/mcl_formspec/API.md
+++ b/mods/HUD/mcl_formspec/API.md
@@ -0,0 +1,40 @@
+# MineClone2 Formspec API
+
+## `mcl_formspec.label_color`
+
+Contains the color used for formspec labels, currently `#313131`.
+
+## `mcl_formspec.get_itemslot_bg(x, y, w, h)`
+
+Get the background of inventory slots (formspec version = 1)
+
+ex:
+
+```lua
+local formspec = table.concat({
+	mcl_formspec.get_itemslot_bg(0, 0, 5, 2),
+	"list[current_player;super_inventory;0,0;5,2;]",
+})
+```
+
+## `mcl_formspec.get_itemslot_bg_v4(x, y, w, h, size, texture)`
+
+Get the background of inventory slots (formspec version > 1)
+
+Works basically the same as `mcl_formspec.get_itemslot_bg(x, y, w, h)` but have more customisation options:
+
+- `size`: allow you to customize the size of the slot borders, default is 0.05
+- `texture`: allow you to specify a custom texture tu use instead of the default one
+
+ex:
+
+```lua
+local formspec = table.concat({
+	mcl_formspec.get_itemslot_bg_v4(0.375, 0.375, 5, 2, 0.1, "super_slot_background.png"),
+	"list[current_player;super_inventory;0.375,0.375;5,2;]",
+})
+```
+
+## `mcl_formspec.itemslot_border_size`
+
+Contains the default item slot border size used by `mcl_formspec.get_itemslot_bg_v4`, currently 0.05
diff --git a/mods/HUD/mcl_formspec/init.lua b/mods/HUD/mcl_formspec/init.lua
index 69ef23e08..d449e937f 100644
--- a/mods/HUD/mcl_formspec/init.lua
+++ b/mods/HUD/mcl_formspec/init.lua
@@ -2,6 +2,7 @@ mcl_formspec = {}
 
 mcl_formspec.label_color = "#313131"
 
+---Get the background of inventory slots (formspec version = 1)
 ---@param x number
 ---@param y number
 ---@param w number
@@ -32,6 +33,7 @@ end
 
 mcl_formspec.itemslot_border_size = 0.05
 
+---Get the background of inventory slots (formspec version > 1)
 ---@param x number
 ---@param y number
 ---@param w integer