> ## Documentation Index
> Fetch the complete documentation index at: https://docs.artbucket.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Standards

> The open formats a brand is served in, and how its rules become each of them.

A brand's rules are its source. Everything else is drawn from them, in
formats other tools already read, so nobody has to copy a hex code by hand:

| Format | For | Where |
| - | - | - |
| [AdCP brand.json](/guides/brand-as-code/brand-json) | Ad tech and agents that look a brand up by its domain | BrandHub, `/{org}/{brand}/brand.json`; a verified domain's `/.well-known/brand.json`. Read too, to start a brand |
| [W3C design tokens](#w3c-design-tokens) (DTCG) | Style Dictionary, Tokens Studio, Figma importers | `?format=json` |
| [Stylesheets and themes](#token-formats) | CSS, Sass, Less, Tailwind, TypeScript, shadcn/ui, Material UI, Chakra UI | `?format=css`, and the others |
| [DESIGN.md](#designmd) | Coding agents | `?format=designmd` |
| [llms.txt](#llmstxt) | Any agent that reads the web | BrandHub, `/{org}/{brand}/llms.txt` and `/llms.txt` |
| [rules.json](#rulesjson) | Anything that wants every rule, losslessly | BrandHub, `/{org}/{brand}/rules.json` |
| [MCP](#mcp) | Agents that ask questions, in chat apps and editors | `/api/v1/mcp` |
| [The brand folder](/guides/brand-as-code/format) | Git, review, scripts | The sync API and the CLI |

## Where tokens come from

The same formats come from two places:

| | Reads | Who |
| - | - | - |
| `GET /api/v1/brand/tokens?format=css&brand=acme` | The brand as it stands now, draft included | Anyone who can read the workspace, with a key or signed in |
| `https://{hub}/{org}/{brand}/tokens?format=css` | The latest release, or `@{n}` for one: `/{org}/{brand}@4/tokens` | Anyone, for a public brand on [BrandHub](/guides/portals#brandhub) |

Both take `context`: `?context=dark-background` gives each rule's version for
that context and the default of the rest. Without it, every rule's default.
In the app, the brand's **Tokens and rules** tab shows every format, and
**Use this brand** copies their addresses.

On BrandHub, file URLs inside an answer (font files, logos) are signed for a
day, and the answer itself may be cached for an hour: fetch it again rather
than keeping its URLs.

## W3C design tokens

`format=json` is the [Design Tokens Format](https://www.designtokens.org/)
(DTCG 2025.10). Each rule's dotted key is its path: `color.primary` is
`{ "color": { "primary": { ... } } }`.

| Rule | Token |
| - | - |
| color | `$type: color`, `$value` in sRGB: `components` from 0 to 1, `alpha` when below 1, and `hex` |
| color with `spec.gradient` | The color as above, and `{key}Gradient` beside it: `$type: gradient`, stops by reference (`{color.primary}`) or by value, positions from 0 to 1; kind, angle and the CSS in `$extensions["com.artbucket"]` |
| number | `$type: number` |
| type scale (a list of numbers) | Steps `1`, `2`, ... each `$type: dimension` in px |
| font | A group: `fontFamily`, `fontSize` (px) and `fontWeight` when set; the files in `$extensions["com.artbucket"].files`, each with its URL, weight, style and media type |
| a rule carrying a font's file | `fontFamily` (and `fontWeight`) as references to that font: a heading style set in the brand's face |
| text, and lists that aren't a scale | Left out: they are guidance, not values |

A rule's `usage` becomes its `$description`.

```json theme={null}
{
  "color": {
    "primary": {
      "$type": "color",
      "$value": { "colorSpace": "srgb", "components": [0.1216, 0.4353, 0.9216], "hex": "#1f6feb" },
      "$description": "Buttons, links and the mark's tile."
    }
  },
  "type": {
    "heading": {
      "fontFamily": { "$type": "fontFamily", "$value": "Inter" },
      "fontSize": { "$type": "dimension", "$value": { "value": 40, "unit": "px" } },
      "fontWeight": { "$type": "fontWeight", "$value": 700 },
      "$extensions": {
        "com.artbucket": {
          "files": [{ "url": "https://app.example.com/a/6f1c...", "weight": 700, "style": "normal", "mime": "font/woff2" }]
        }
      }
    }
  }
}
```

A key that is both a token and the start of another key (`color.primary` and
`color.primary.dark`) nests the second inside the first, which DTCG readers
refuse: name one of them otherwise (`color.primaryDark`).

## Token formats

| `format` | File | |
| - | - | - |
| `css` | `{brand}.tokens.css` | Custom properties on `:root`, with `@font-face` for every font file |
| `scss` | `_{brand}-tokens.scss` | Sass variables and `@font-face` |
| `less` | `{brand}.tokens.less` | Less variables and `@font-face` |
| `tailwind` | `{brand}.theme.css` | A Tailwind CSS 4 `@theme`: utilities like `bg-primary` and `font-headings` |
| `tailwind3` | `tailwind.{brand}.js` | `theme.extend` for a Tailwind CSS 3 config |
| `ts` | `{brand}.tokens.ts` | One typed object, for styled-components, Emotion, vanilla-extract, React Native |
| `shadcn` | `{brand}.shadcn.css` | Colors named like shadcn/ui's take their place, with readable foregrounds |
| `mui` | `{brand}.mui-theme.ts` | A Material UI `createTheme` with the palette and typography |
| `chakra` | `{brand}.chakra-system.ts` | A Chakra UI 3 system over the defaults |
| `json` | `{brand}.tokens.json` | [W3C design tokens](#w3c-design-tokens) |
| `designmd` | `DESIGN.md` | [DESIGN.md](#designmd) |

Names follow keys: `logo.minClearSpace` is `--logo-min-clear-space` in CSS.
Colors, numbers, fonts (family, size, weight and their files) and type
scales become tokens; a font's files are loaded from Artbucket by
`@font-face`, with each file's weight and style read from its name
(`Inter-BoldItalic.woff2`). A number is written as it is, without its
`spec.unit`.

```css theme={null}
:root {
  /* Buttons, links and the mark's tile. */
  --color-primary: #1f6feb;
  --type-heading-font-family: "Inter";
  --type-heading-font-size: 40px;
  --type-heading-font-weight: 700;
  --type-scale-1: 12px;
  --logo-min-size: 24;
}
```

## DESIGN.md

`format=designmd` is a [DESIGN.md](https://github.com/google-labs-code/design.md)
(Google Labs, version alpha), to keep at a repository's root for coding
agents. It is the one format that carries guidance as well as values:

* **Front matter:** `colors` by their local name (`color.primary` is
  `primary`; when no color is named primary, `primary` refers to the first),
  `typography` per face (family, size, weight), `rounded` for number rules
  named like a radius (in px), and `spacing` for ones named like a gap,
  margin or padding.
* **Prose:** Overview (text and lists of any other group), Colors,
  Typography, Layout, Shapes, and Do's and Don'ts, from lists whose key reads
  as a do or a don't.

## llms.txt

Every public brand on BrandHub has `/{org}/{brand}/llms.txt`: the brand in
words for an agent, with who listed it and whether that is verified, links to
its other files, its portal's terms, and every rule by context, each with its
files. BrandHub's own `/llms.txt` says how an agent finds a brand there, and
lists them.

A domain's own `/llms.txt` is the first place the public
[Brand Agent Score](/guides/portals#a-public-brand-agent-score) looks: link
your brand.json, your tokens and your MCP server from it.

## rules.json

`/{org}/{brand}/rules.json` is the listing as data, lossless: the release,
who listed it, its versions, its portal and terms, and every rule with its
key, label, context, type, value, spec, usage and files, signed for a day.

```json theme={null}
{
  "data": {
    "org": "acme",
    "brand": "acme",
    "name": "Acme",
    "version": 4,
    "url": "https://hub.example.com/acme/acme",
    "rules": [
      { "key": "color.primary", "label": "Acme blue", "context": null, "type": "color", "value": "#1f6feb", "spec": { "pair": "color.background" }, "usage": "Buttons, links and the mark's tile.", "assets": [] }
    ]
  }
}
```

## MCP

`/api/v1/mcp` serves the same brand to agents that connect: `brand_rules`
for a context, `get_theme`, `list_pages` and `get_page`, and the rules and
pages as resources (`artbucket://brands/{slug}/rules/{context}`). See
[MCP](/developers/mcp).

## How BrandHub files are served

* Public brands only, from the latest release, or the one `@{n}` names.
* Keyless, with `Access-Control-Allow-Origin: *`, cached up to an hour.
* A community listing (its organization proved neither a domain nor a
  GitHub account) answers with `X-Robots-Tag: noindex`.
* Each read but the badge's is a pull, counted in
  [Insights](/guides/insights).