# Agentic Resource Discovery (ARD)

A file at /.well-known/ard.json listing the agents, tools and APIs a site offers, each with a stable name.

**[Capabilities](/docs/capabilities)** · checked once per host (item type `ard`) · 9 checks that can fail it

It gives each agent, MCP server or API a site offers a stable, domain-anchored name and says where to find it, so an agent or a registry can discover them from one address. Google's Lighthouse checks it in Chrome DevTools and PageSpeed Insights, and an entry that breaks the rules is rejected rather than half-read.

## Adoption

**Early production** (L2)

Several independent organisations run it in production, though it is still niche on the open web. Direction of travel: ▲ rising, as of 2026-10-14.

496 files on 382 hosts in a 2026-10-14 survey, most still at the older ai-catalog.json address, and Lighthouse 13.5.0 (2026-09-18) audits it. The specification is a v0.91 Proposal from Google, Microsoft and Hugging Face authors.

| Adopter | Depth | Evidence |
|---|---|---|
| Hugging Face | production | [huggingface.co](https://huggingface.co/.well-known/ai-catalog.json) |
| Supabase | production | [supabase.com](https://supabase.com/.well-known/ard.json) |
| Vercel | production | [vercel.com](https://vercel.com/.well-known/ai-catalog.json) |
| Zapier | production | [zapier.com](https://zapier.com/.well-known/ai-catalog.json) |

## What we check

Absence is never a finding: every check below runs only when this technology is detected, so a site that has not
adopted this is not assessed on it and appears in no report.

| Check | Kind | Raises | On whose authority |
|---|---|---|---|
| ARD Malformed Document | high severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Entry Missing Identifier | high severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Entry Missing Type | high severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Entry URL And Data | high severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Entry Missing Display Name | medium severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Entry Invalid Identifier | medium severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Entry Type Not Media Type | medium severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Invalid Trust Manifest | medium severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Trust Identity Mismatch | medium severity | conformance, usability | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |
| ARD Predecessor Path Only | informational | nothing | specification: [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) |

## Examples

Both run through the same checks as a live scan: the first passes, the second is flagged.

**Correct**

```json
{
  "entries": [
    {
      "identifier": "urn:air:example.com:assistant",
      "displayName": "Example Assistant",
      "type": "application/mcp-server-card+json",
      "url": "https://example.com/.well-known/mcp/server-card.json",
      "representativeQueries": ["Track my order", "Find a product in my size"],
      "trustManifest": { "identity": "did:web:example.com" }
    },
    {
      "identifier": "urn:air:example.com:api:orders",
      "displayName": "Orders API",
      "type": "application/openapi+json",
      "url": "https://api.example.com/openapi.json"
    }
  ]
}
```

**Present but wrong**

```json
{
  "entries": [
    {
      "identifier": "urn:ai:example.com:assistant",
      "type": "documentation",
      "url": "https://example.com/assistant",
      "data": { "inline": true }
    },
    {
      "displayName": "Orders API",
      "url": "https://api.example.com/openapi.json"
    },
    {
      "identifier": "urn:air:example.com:search",
      "displayName": "Search",
      "type": "application/json",
      "url": "https://example.com/search.json",
      "trustManifest": { "identity": "did:web:another-company.example" }
    },
    {
      "identifier": "urn:air:example.com:labs",
      "displayName": "Labs",
      "type": "application/json",
      "url": "https://example.com/labs.json",
      "trustManifest": { "identity": { "principalName": "example.com" } }
    }
  ]
}
```

## Specifications

| Document | Revision | Kind |
|---|---|---|
| [Agentic Resource Discovery (ARD) specification](https://github.com/ards-project/ard-spec/blob/main/spec/ard.md) | Version 0.91, Proposal (2026-08-26) | specification |
| [Lighthouse 13.5.0 release, which added the ARD audit](https://github.com/GoogleChrome/lighthouse/releases/tag/v13.5.0) | Living document | guidance |

Last re-read against the published documents: 2026-10-14.