start_tributary_interaction_effect

start_tributary_interaction_effect = {
	# Setup truces depending on how the tributary relationship was created
	$TRIBUTARY$ = { save_scope_as = tributary_loc }
	$SUZERAIN$ = { save_scope_as = suzerain_loc }

	#Mandala Tributaries
	if = {
		limit = {
			should_be_mandala_tributary_trigger = {
				SUZERAIN = $SUZERAIN$
				TRIBUTARY = $TRIBUTARY$
			}
			trigger_if = {
				limit = { exists = scope:tributary_war }
				$SUZERAIN$ = {
					AND = {
						house = { has_house_head_parameter = can_make_mandala_tributaries_via_war }
						is_house_head = yes
					}
				}
			}
		}
		$TRIBUTARY$ = {
			if = {
				limit = { government_has_flag = government_is_tribal }
				start_tributary = {
					contract_group = tributary_mandala_tribal
					suzerain = $SUZERAIN$
				}
				if = {
					limit = {
						OR = {
							scope:high_obligations ?= yes
							exists = scope:tributary_war
						}
					}
					if = {
						limit = { is_tributary = yes } # suppress error logging
						hidden_effect = {
							tributary_contract_set_obligation_level = {
								type = mandala_government_taxes
								level = 3
							}
							tributary_contract_set_obligation_level = {
								type = mandala_government_prestige
								level = 2
							}
							tributary_contract_set_obligation_level = {
								type = mandala_government_levies
								level = 3
							}
						}
					}
					custom_tooltip = high_mandala_tribute_taxes
					custom_tooltip = high_mandala_tribute_prestige
					custom_tooltip = high_mandala_tribute_levies
				}
				else_if = {
					limit = { scope:low_obligations ?= yes }
					if = {
						limit = { is_tributary = yes } # suppress error logging
						hidden_effect = {
							tributary_contract_set_obligation_level = {
								type = mandala_government_taxes
								level = 0
							}
							tributary_contract_set_obligation_level = {
								type = mandala_government_prestige
								level = 0
							}
							tributary_contract_set_obligation_level = {
								type = mandala_government_levies
								level = 0
							}
						}
					}
					custom_tooltip = exempt_mandala_tribute_taxes
					custom_tooltip = low_mandala_tribute_prestige
					custom_tooltip = exempt_mandala_tribute_levies
				}
				else = {
					if = {
						limit = { is_tributary = yes } # suppress error logging
						hidden_effect = {
							tributary_contract_set_obligation_level = {
								type = mandala_government_taxes
								level = 2
							}
							tributary_contract_set_obligation_level = {
								type = mandala_government_prestige
								level = 2
							}
							tributary_contract_set_obligation_level = {
								type = mandala_government_levies
								level = 1
							}
						}
					}
					custom_tooltip = normal_mandala_tribute_taxes
					custom_tooltip = normal_mandala_tribute_prestige
					custom_tooltip = low_mandala_tribute_levies
				}

				if = {
					limit = { is_tributary = yes } # suppress error logging
					tributary_contract_set_obligation_level = {
						type = mandala_suzerain_war_participation_guarantee
						level = 1
					}
				}
			}
			else = {
				start_tributary = {
					contract_group = tributary_mandala
					suzerain = $SUZERAIN$
				}
				if = {
					limit = {
						OR = {
							scope:high_obligations ?= yes

As written in game/common/scripted_effects/00_interaction_effects.txt.