Lint rules

Lint rules point out style problems and likely mistakes; errors the checker reports are not lint. A project can change any rule's severity in mms.json, and Lint rules in the guides explains how, and how to silence one.

Rule	Default	Reports
`accidental-markup`	hint	A style mark in text that is never closed, such as the `` of "5 3", so it is written as the character itself. The fix puts a backslash before it, which says so.
`book-page-overflow`	warning	A Book page with more text than the book screen shows: 14 lines of about 19 characters. The game cuts the rest off. Widths are measured with the vanilla font, so text outside ASCII is a close guess.
`constant-expression`	hint	An arithmetic expression of number literals can be written as its value.
`custom-item-as-base`	hint	A Book used where the game takes a plain item id, such as a recipe ingredient or an item tag. It stands for written_book there, so any written book matches.
`deprecated`	warning	A use of a declaration whose doc comment has a `@deprecated` tag.
`external-asset`	warning	An id of a texture, sound or structure in the project's namespace that no Texture, Sound or StructureFile call in the project provides. The pack still loads, but the file must come from another pack.
`jigsaw-facing`	warning	A jigsaw block that can never join its target: every jigsaw block with its target name in its pool faces a way it cannot meet. The game turns pieces only about the y axis, so a block facing up joins only one facing down, and a sideways block only a sideways one.
`jigsaw-fit`	warning	An internal jigsaw block (the block in front of it is inside its own piece, such as an arch mount on a road, or a jigsaw inset by a block by mistake) whose pool has pieces that stick out of the piece however they are turned. The game only places a piece joined at an internal jigsaw wholly inside its parent, so those pieces are never placed there. Height is not checked for terrain_matching pieces.
`jigsaw-overlap`	info	A jigsaw block that can never grow when its piece joins a given parent: every piece its pool and the pool's fallback could place there overlaps the parent or the piece itself, however it is turned, and the game never places overlapping pieces. A junction narrower than the roads around it is the usual cause. Only certain cases are reported: every piece involved is a rigid project structure file with a known size and facing, and no pool involved has an empty or feature element.
`jigsaw-unknown-name`	warning	A jigsaw block in a structure file that StructureFile("...") includes whose name or target is in a namespace with JigsawHole declarations, but is not one of them: most likely a typo made in the game's jigsaw screen. The quick fix declares it. Projects that declare no JigsawHole in a namespace are not checked there.
`jigsaw-unknown-pool`	warning	A jigsaw block in a structure file that StructureFile("...") includes draws from a pool in the project's namespace that no TemplatePool declares. The game skips the jigsaw, so the structure stops growing there. The quick fix declares the pool.
`jigsaw-unreachable-target`	warning	A jigsaw block whose target no piece of its pool can join: none of the pool's structure files has a jigsaw block with that name, or the pool has no pieces. Only pools whose pieces are all the project's own structure files are checked.
`overrides-vanilla`	info	A declaration in the minecraft namespace replaces the vanilla resource with the same id.
`quoted-name`	hint	An id or enum name in quotes can be written bare: `minecraft:stone` or `stone` rather than "minecraft:stone".
`redundant-namespace`	hint	A `minecraft:` prefix that can be dropped: `stone` means `minecraft:stone` unless the project declares its own `stone`.
`unused`	hint	A worldgen piece, predicate or item modifier that nothing in the project references, so the game never uses it, or a const, Template, Type or Blueprint that nothing names. A TemplatePool counts as used when a jigsaw block in one of the project's structure files draws from it.
`unused-asset`	info	A .png, .ogg or .nbt file in the project that no Texture, Sound or StructureFile call and no `icon` uses, so the packs leave it out. It is reported on the file itself (in VS Code's Problems panel, by `mms check`, and in the web editor's asset list), and not while the project has errors.
`use-shorthand`	hint	An object literal that has a shorter MMS form: an item entry as its id, `1..3` for a uniform provider or bounds, `diamond * 4` for a stack, a trigger call for a criterion, and `&&`, `\|\|` and `!` for conditions.