Managing Mods

Mods are declared in the [mods] table of mc.toml and installed when the instance starts. Each entry maps a mod's identifier on the mod registry to the version to install:

[minecraft]
version = "..."
loader = "fabric"

[mods]
lithium = "..."

A mod loader must be configured under [minecraft] for mods to be installed; without one, the [mods] table is ignored. See The Manifest Format for every supported form of a mod entry, including mods fetched from a direct URL.

Adding and removing mods

mc add and mc remove edit the [mods] table for you. mc add looks the mod up on the registry and pins the latest version compatible with the configured Minecraft version and loader:

$ mc add sodium lithium
$ mc remove sodium

Updating mods

mc update re-pins mods to the latest compatible version — every mod in the manifest, or only the ones you name:

$ mc update
$ mc update lithium

Mods fetched from a direct URL have no version to compare and are skipped.

How mods are installed

Changes to [mods] take effect the next time the instance starts. On startup, mc resolves each entry — including its required dependencies — and records the result in the mc.lock lockfile. It then downloads any mod that is missing and deletes any mod that is no longer in the lockfile.

Two consequences of this are worth knowing:

• You do not need to declare a mod's dependencies; they are resolved and installed automatically.
• The instance's mods directory is fully managed by mc. A jar placed there by hand is removed on the next start. To install a mod that is not on the registry, declare it in the manifest with a url entry instead.