> ## Documentation Index
> Fetch the complete documentation index at: https://agenticadvertisingorg-snap-format-preview-links.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Accessibility

> AdCP accessibility support lets formats declare WCAG conformance levels and requires accessible assets like alt text and captions.

AdCP supports accessibility at two levels: formats declare the conformance level of their rendered output, and assets carry the metadata needed to achieve it.

## How It Works

Accessibility in advertising creatives depends on who controls the rendering:

* **Format-rendered creatives** (image + headline + CTA): The format controls the output. It can guarantee contrast ratios, keyboard navigation, and ARIA landmarks — it just needs the right inputs from the creative (alt text for images, captions for video, etc.).

* **Opaque creatives** (HTML bundles, JavaScript tags): The format can't inspect or modify the content. The asset must self-declare its accessibility properties.

AdCP handles both cases through the format's `accessibility` object and per-asset-type accessibility metadata.

## Format Accessibility

Formats declare their accessibility posture through the `accessibility` object:

### `accessibility.wcag_level`

The WCAG conformance level that creatives produced by this format will meet. Values: `A`, `AA`, `AAA`.

For format-rendered creatives, this is a guarantee from the format. For opaque creatives, this reflects the level the format requires assets to self-certify to.

### `accessibility.requires_accessible_assets`

When `true`, all assets with accessibility-relevant fields must include those fields. This is the enforcement mechanism — it tells validation to treat optional accessibility fields as required.

```json theme={null}
{
  "format_id": {
    "agent_url": "https://creative.adcontextprotocol.org",
    "id": "display_300x250"
  },
  "name": "Display Banner 300x250",
  "accessibility": {
    "wcag_level": "AA",
    "requires_accessible_assets": true
  },
  "assets": [
    {
      "item_type": "individual",
      "asset_id": "hero_image",
      "asset_type": "image",
      "required": true,
      "requirements": {
        "min_width": 300,
        "max_width": 300,
        "min_height": 250,
        "max_height": 250,
        "formats": ["jpg", "png", "webp"]
      }
    },
    {
      "item_type": "individual",
      "asset_id": "headline",
      "asset_type": "text",
      "required": true,
      "requirements": {
        "max_length": 90
      }
    }
  ]
}
```

This format guarantees WCAG AA output and requires `alt_text` on the image asset (because `alt_text` is marked as an accessibility field on the image asset type).

## Asset Accessibility Fields

Each asset type defines which of its fields are accessibility-relevant using the `x-accessibility` schema marker. These fields are always optional by default, but become required when the format sets `accessibility.requires_accessible_assets: true`.

### Inspectable Assets

These assets provide structured data that the format uses to render accessibly.

| Asset Type | Accessibility Fields    | Purpose                             |
| ---------- | ----------------------- | ----------------------------------- |
| **Image**  | `alt_text`              | Alternative text for screen readers |
| **Video**  | `captions_url`          | URL to captions file (WebVTT, SRT)  |
|            | `transcript_url`        | URL to text transcript              |
|            | `audio_description_url` | URL to audio description track      |
| **Audio**  | `transcript_url`        | URL to text transcript              |

**Example** — video asset in a manifest for an accessible format:

```json theme={null}
{
  "creative_id": "brand_video_001",
  "format_id": {
    "agent_url": "https://creative.adcontextprotocol.org",
    "id": "video_30s_hosted"
  },
  "assets": {
    "video_file": {
      "url": "https://cdn.example.com/video.mp4",
      "width": 1920,
      "height": 1080,
      "duration_ms": 30000,
      "captions_url": "https://cdn.example.com/video.vtt",
      "transcript_url": "https://cdn.example.com/video-transcript.txt",
      "audio_description_url": "https://cdn.example.com/video-ad.mp3"
    }
  }
}
```

### Opaque Assets

HTML and JavaScript assets are black boxes — the format can't inspect their rendering. These assets carry an `accessibility` object with self-declared properties.

| Field                  | Type    | Description                                                       |
| ---------------------- | ------- | ----------------------------------------------------------------- |
| `alt_text`             | string  | Text alternative describing the creative content                  |
| `keyboard_navigable`   | boolean | Creative can be fully operated via keyboard                       |
| `motion_control`       | boolean | Respects `prefers-reduced-motion` or provides pause/stop controls |
| `screen_reader_tested` | boolean | Creative has been tested with screen readers                      |

**Example** — HTML creative with accessibility declarations:

```json theme={null}
{
  "creative_id": "rich_media_001",
  "format_id": {
    "agent_url": "https://publisher.com",
    "id": "rich_media_expandable"
  },
  "assets": {
    "creative_html": {
      "content": "<div class='ad-container'>...</div>",
      "version": "HTML5",
      "accessibility": {
        "alt_text": "Interactive product carousel showing summer collection",
        "keyboard_navigable": true,
        "motion_control": true,
        "screen_reader_tested": true
      }
    }
  }
}
```

Self-declared accessibility is a trust claim. Platforms may independently validate these properties — that is outside the scope of the protocol.

### Third-Party Tags

VAST and DAAST assets wrap video and audio delivered by third parties. They carry accessibility fields alongside their existing tag properties.

| Asset Type | Accessibility Fields                    |
| ---------- | --------------------------------------- |
| **VAST**   | `captions_url`, `audio_description_url` |
| **DAAST**  | `transcript_url`                        |

### Assets Without Accessibility Fields

Some asset types don't produce standalone rendered content and have no accessibility fields. When a format sets `accessibility.requires_accessible_assets: true`, these are effectively no-ops:

* **Text** — rendered by the format
* **Markdown** — rendered by the format
* **CSS** — styles, not content
* **URL** — links, not rendered content
* **Webhook** — server-side

## Discovering Accessible Formats

Buyers can filter for accessible formats using the `wcag_level` parameter in `list_creative_formats`:

```json theme={null}
{
  "wcag_level": "AA",
  "asset_types": ["image", "text"]
}
```

This returns formats that meet at least WCAG AA conformance and accept image and text assets. The filter uses "at least" logic: requesting `AA` returns formats with `AA` or `AAA`.

## Implementation Notes

**Enforcement is application-level.** The `x-accessibility` marker is a JSON Schema extension keyword. Standard JSON Schema validators ignore it — enforcement of `accessibility.requires_accessible_assets` must be implemented in application code that scans asset schemas for `x-accessibility: true` fields and validates their presence.

**For format implementers:**

* Set `accessibility.wcag_level` only when you can substantiate the claim — through your own rendering guarantees or by requiring accessible assets
* If your format renders from structured inputs, ensure your rendering pipeline meets the declared WCAG level (contrast, keyboard nav, ARIA)
* If your format wraps opaque assets, `accessibility.requires_accessible_assets: true` ensures the inputs carry the right declarations

**For creative producers:**

* When submitting to a format with `accessibility.requires_accessible_assets: true`, include all accessibility fields for your asset types
* For opaque assets, test accessibility properties before declaring them
* Provide captions and transcripts as separate hosted files, not embedded in the asset

## Related Documentation

* [Creative Formats](/docs/creative/formats) — Format structure and requirements
* [Asset Types](/docs/creative/asset-types) — Asset specifications and payload schemas
* [Creative Manifests](/docs/creative/creative-manifests) — Pairing assets with formats
* [list\_creative\_formats](/docs/creative/task-reference/list_creative_formats) — Format discovery with filtering