mcf-tags

name	mcf-tags
description	Create and modify Minecraft Java Edition tag definitions. Use when grouping game elements (blocks, items, entities, functions, biomes, etc.) for use in recipes, loot tables, predicates, commands, and world generation. Covers tag file format, loading behavior, and all available tag types for version 26.1.2.
license	MIT
compatibility	opencode
metadata	{"version":"1.0","game-version":"26.1.2","category":"minecraft-datapack"}

Minecraft Tags (Data Pack Tags)

File Location

data/<namespace>/tags/<registry_path>/<tag_name>.json

For functions (not a registry): data/<namespace>/tags/function/<tag_name>.json

Tag File Format

{
  "replace": false,
  "values": [
    "minecraft:oak_log",
    "minecraft:birch_log",
    "#namespace:other_tag",
    { "id": "optional:item", "required": false }
  ]
}

Fields:

• replace (default: false): true = completely override lower-priority tags; false = merge
• values (required): Array of entries
• required (default: true): false = silently ignore missing entries

Entry Types

Each entry can be:

// Simple ID
"namespace:value"

// Tag reference (with # prefix)
"#namespace:other_tag"

// Object with optional flag
{ "id": "namespace:value", "required": false }

Tag ID Format

When referencing tags in commands, recipes, etc., prefix with #:

#minecraft:logs          # Block tag
#namespace:my_functions   # Function tag
#minecraft:skeletons      # Entity type tag

Loading & Priority

• Load bottom-up (higher data pack priority overrides lower)
• If upper replace: true, lower data is completely discarded
• If upper replace: false, values are merged
• Invalid lower tag (missing entries) makes upper tag invalid too
• Circular tag references cause load failure

Extension vs Replacement Example

// Extend (append to existing):
// data/minecraft/tags/block/sword_efficient.json
{ "values": ["#minecraft:wool"] }

// Replace (override completely):
// data/minecraft/tags/block/beacon_base_blocks.json
{ "replace": true, "values": ["minecraft:lodestone"] }

Available Tag Types (v26.1.2)

Game Element Tags

Registry Path	Description
block	Block tags
item	Item tags
entity_type	Entity type tags
fluid	Fluid tags
game_event	Game event tags

Definition Tags

Registry Path	Description
banner_pattern	Banner pattern tags
chat_type	Chat type tags
damage_type	Damage type tags
dialog	Dialog tags
enchantment	Enchantment tags
instrument	Goat horn instrument tags
painting_variant	Painting variant tags
point_of_interest_type	Point of interest type tags
potion	Potion effect tags
timeline	Timeline tags
villager_trade	Villager trade tags

World Generation Tags

Registry Path	Description
worldgen/biome	Biome tags
worldgen/configured_feature	Configured feature tags
worldgen/flat_level_generator_preset	Superflat preset tags
worldgen/structure	Structure tags
worldgen/world_preset	World preset tags

Function Tags

Registry Path	Description
function	Function tags (not a registry)

No tags exist for: advancements, recipes, structure templates.

Special Function Tags

#minecraft:load

// data/minecraft/tags/function/load.json
{
  "values": ["mypack:init", "mypack:setup"]
}

• Executed on world load, server start, and /reload
• Runs BEFORE players join - cannot target players
• Cannot use /tellraw, /title, etc. (no players online)

#minecraft:tick

// data/minecraft/tags/function/tick.json
{
  "values": ["mypack:tick_handler"]
}

• Executed at the start of EVERY game tick
• Use for continuous game loops
• Be careful with performance - minimize heavy operations

Common Tag Usage Examples

In Recipe (item tag)

{
  "type": "minecraft:crafting_shaped",
  "key": { "#": { "tag": "minecraft:logs" } },
  "pattern": ["##", "##"],
  "result": { "id": "minecraft:crafting_table" }
}

In Loot Table (entry with tag)

{
  "type": "minecraft:tag",
  "name": "minecraft:arrows",
  "expand": false
}

In Predicate

{
  "condition": "minecraft:location_check",
  "predicate": {
    "biome": "#minecraft:is_forest"
  }
}

In Command

execute if block ~ ~-1 ~ #minecraft:dirt run say Standing on dirt-type block
execute if entity @e[type=#minecraft:skeletons] run say Skeleton nearby
function #mypack:daily_tasks

In World Generation (biome tag)

// Referenced in multi_noise_biome_source_parameter_list
{
  "biome": "#minecraft:is_overworld"
}

In Enchantment Definition

{
  "supported_items": "#minecraft:enchantable/sword",
  "exclusive_set": "#minecraft:exclusive_set/damage"
}

Important Tag Directories (v26.1.2)

Note: Tag directories use singular forms since 1.21:

• tags/block (NOT tags/blocks)
• tags/item (NOT tags/items)
• tags/entity_type (NOT tags/entity_types)
• tags/fluid (NOT tags/fluids)
• tags/game_event (NOT tags/game_events)
• tags/function (NOT tags/functions)