SysTools

adds a few new commands like /shoot, /itemcommand (links a command to an item you're holding), /multicmd (a few commands in one using ;, like /multicmd say hi; say hello -> hi/hello)
and a new MineScript Language
it uses basic minecraft commands with a custom logic chain

there's a few examples:

event Player_Chat [forge_armor]:
    has_funds = player.Inventory.has("diamond")
    if has_funds == true:
        clear @p minecraft:diamond 1
        tellraw @p {"text":"[Blacksmith] I took your Diamond. Let me forge that for you...","color":"yellow"}
        execute positioned ~ ~ ~ run playsound block.anvil.use master @p
        wait 2 seconds
        execute positioned ~ ~ ~ run playsound block.anvil.use master @p
        
        wait 2 seconds
        give @p minecraft:iron_chestplate 1
        tellraw @p {"text":"[Blacksmith] Here is your new armor! Have a safe journey.","color":"green"}
        execute positioned ~ ~ ~ run playsound entity.player.levelup master @p
    else:
        tellraw @p {"text":"[Blacksmith] You don't have a Diamond! No money, no armor.","color":"red"}
        execute positioned ~ ~ ~ run playsound entity.villager.no master @p

event Entity_Death [minecraft:zombie]:
    give @p diamond 1

event Player_Sneak:
    shoot fireball 2.0

event Player_Chat [hi]:
    tellraw @p {"text":"Hello World!","color":"green"}

event Player_Sneak:
    if entity @p[distance=..5]:
        summon lightning_bolt ~ ~ ~
    else:
        say No MSE here

event Player_Sneak:
    has_diamonds = player.Inventory.has("diamond")
    if has_diamonds == true:
        say You have diamonds!
        give @p gold_ingot 1