Commands

The server publishes its complete Brigadier command graph to the client with Commands (0x10) (clientbound, Play state). The client uses this graph to drive in-chat tab-completion, parse-time error highlighting, and to filter /-prefixed input from the chat box. The client never executes commands locally — it sends them to the server as Chat Command packets — but it must be able to recognize the syntax.

Tab-completion uses Command Suggestions Request (0x0F) and Command Suggestions (0x0F). Their byte-level layouts live on the packet pages; this page documents the Brigadier sub-payloads they reference.

Node graph

The graph is sent as a flat array of nodes plus a root index. Children and redirects are referenced by integer indices into that array.

Node

Field	Type	Notes
Flags	Byte	See flags.
Children count	VarInt
Children indices	VarInt × count	Indices into the node array.
Redirect index	VarInt (optional)	Present iff `flags & 0x08`.
Name	String (optional)	Present for literal/argument nodes.
Parser	sub-payload (optional)	Present for argument nodes only — see Parsers.
Suggestions identifier	Identifier (optional)	Present iff `flags & 0x10`.

Flags byte

bits 0..1   Node type:
              0 = root
              1 = literal
              2 = argument
bit  2 (0x04)  is_executable    — node can terminate a command.
bit  3 (0x08)  has_redirect     — node redirects to the node at `redirect index`.
bit  4 (0x10)  has_suggestions  — argument node uses an explicit suggestions provider
                                  identified by `Suggestions identifier`.
bit  5 (0x20)  is_restricted    — node is permission-restricted; the client should
                                  display it dimmed and not suggest it.
bits 6..7      reserved (must be 0).

For a root node (type 0): no name, no parser, no suggestion id. For a literal node (type 1): Name is the literal token (e.g. "give"). For an argument node (type 2): Name is the parameter name (used in /help-style hints), then Parser follows, then Suggestions identifier if has_suggestions.

Parsers

The argument node's Parser sub-payload starts with a VarInt — the parser's numeric ID into the minecraft:command_argument_type registry — followed by parser-specific bytes.

The parser registry is fixed for a given protocol version. Parsers in 26.1.2:

Identifier	Properties
`brigadier:bool`	none
`brigadier:float`	Flags byte (0x01 has_min, 0x02 has_max), optional Float min, optional Float max.
`brigadier:double`	Flags byte (0x01 has_min, 0x02 has_max), optional Double min, optional Double max.
`brigadier:integer`	Flags byte (0x01 has_min, 0x02 has_max), optional Int min, optional Int max.
`brigadier:long`	Flags byte (0x01 has_min, 0x02 has_max), optional Long min, optional Long max.
`brigadier:string`	VarInt mode (0=single word, 1=quotable phrase, 2=greedy phrase).
`entity`	Flags byte (0x01 single target, 0x02 only players).
`game_profile`	none
`block_pos`	none
`column_pos`	none
`vec3`	none
`vec2`	none
`block_state`	none
`block_predicate`	none
`item_stack`	none
`item_predicate`	none
`color`	none
`hex_color`	none
`component`	none
`style`	none
`message`	none
`nbt_compound_tag`	none
`nbt_tag`	none
`nbt_path`	none
`objective`	none
`objective_criteria`	none
`operation`	none
`particle`	none
`angle`	none
`rotation`	none
`scoreboard_slot`	none
`score_holder`	Flags byte (0x01 allow multiple).
`swizzle`	none
`team`	none
`item_slot`	none
`item_slots`	none
`resource_location`	none
`function`	none
`entity_anchor`	none
`int_range`	none
`float_range`	none
`dimension`	none
`gamemode`	none
`time`	Int min — minimum tick value the parser accepts.
`resource_or_tag`	Identifier — the registry being looked up.
`resource_or_tag_key`	Identifier — registry.
`resource`	Identifier — registry.
`resource_key`	Identifier — registry.
`resource_selector`	Identifier — registry.
`template_mirror`	none
`template_rotation`	none
`heightmap`	none
`loot_table`	none
`loot_predicate`	none
`loot_modifier`	none
`dialog`	none
`uuid`	none

NOTE: When an argument node uses one of vanilla's suggestions providers (rather than the parser's built-in suggestions), flags & 0x10 is set and Suggestions identifier is the provider's identifier. The vanilla providers are minecraft:ask_server, minecraft:all_recipes, minecraft:available_sounds, minecraft:summonable_entities. minecraft:ask_server instructs the client to call back via Command Suggestions Request whenever the user types in that argument.

Validation

The client validates the graph before installing it: every child/redirect index must point to a node already buildable (no forward dangling references after redirect resolution). A malformed graph terminates the connection.

Source: net/minecraft/network/protocol/game/ClientboundCommandsPacket.java, net/minecraft/network/protocol/game/ClientboundCommandSuggestionsPacket.java, net/minecraft/network/protocol/game/ServerboundCommandSuggestionPacket.java, net/minecraft/commands/synchronization/ArgumentTypeInfos.java, net/minecraft/commands/synchronization/SuggestionProviders.java.

ON THIS PAGE

Commands#

Node graph#

Node#

Flags byte#