You shouldn't use the code of a poorly implemented mod as an example to base your mod on. Use this instead (replaces everything, save as base.lua or mod.lua):

return DMod:new("MP% but with actual kick", {
	author = "Anthony",
	description = "Increases the recoil of the mp5 to make it feel stronger.",
	hooks = {{
		"lib/tweak_data/weapontweakdata", function(m)
			local WeaponTweakData = m:hook_class("WeaponTweakData")
			m:post_hook(WeaponTweakData, "_init_data_player_weapons", function(self)
				self.mp5.kick.v.standing = 2.5
				self.mp5.kick.v.crouching = 2.0
				self.mp5.kick.v.steelsight = 2.5
				self.mp5.kick.h.standing = 2.5
				self.mp5.kick.h.crouching = 2.0
				self.mp5.kick.h.steelsight = 2.5
			end)
		end
	}}
})

I left the typo in the id (and implicit name from that) in btw.