# Agentshelf Syntexa CSS Atom Autodiscovery

> Agentshelf Syntexa CSS Atom Autodiscovery is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-02).

Extracts Atom feed autodiscovery hrefs from a public URL or raw HTML by querying link[type='application/atom+xml'] elements, with SSRF protection.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/css-atom?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentshelf-syntexa-css-atom-autodiscovery-f182fa99
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WwrDBQ06Bk-Iq9EvWNVCg

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability agentshelf-syntexa-css-atom-autodiscovery-f182fa99 -d '<json body>'
```

Example prompt: Can you find any Atom feed autodiscovery links on https://example.com/blog? I want the hrefs from the link[type='application/atom+xml'] tags on that page.

## When to prefer this

Use this endpoint when you need to programmatically discover Atom feed URLs from a public webpage or a block of HTML and want SSRF-safe fetching handled server-side. Prefer this over building your own CSS-selector HTML parser when you need a reliable, sandboxed extraction without standing up infrastructure. If a free sandbox alternative (POST /v1/sandbox/css-atom) is available and sufficient, prefer that first to avoid the $0.005 charge.

## Known failure modes

- No Atom autodiscovery links found on the page (empty result)
- SSRF-blocked URL — request to private/internal IP range rejected
- URL fetch failure — target page unreachable or returns non-200
- HTML too large — exceeds 200,000 character limit
- Malformed URL input below minimum length or above 2048 characters
- Payment failure — insufficient USDC balance for $0.005 charge

## How this service works

Call when an agent needs Atom autodiscovery hrefs via link[type='application/atom+xml'] from a public page or HTML (SSRF-safe). Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/css-atom first.

## Output

Returns one or more Atom feed autodiscovery hrefs found in link[type='application/atom+xml'] elements on the given page or HTML, enabling the caller to subscribe to or process the syndication feed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048,
   "minLength": 8,
   "description": "Public page to fetch. The selector or profile is fixed by the SKU. Provide url or html."
  },
  "html": {
   "type": "string",
   "examples": [
    "<!doctype html><html lang=\"en\"><head><title>Hello</title>\n<meta charset=\"utf-8\"><meta name=\"description\" content=\"Desc\">\n<link rel=\"canonical\" href=\"https://example.com/\"><link rel=\"icon\" href=\"/favicon.ico\">\n</head><body><h1>Hello</h1><a href=\"https://example.com/a\">A</a></body></html>"
   ],
   "maxLength": 200000,
   "minLength": 1,
   "description": "HTML to extract from locally. Provide html or url. When both are set, html is used."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentshelf-syntexa-css-atom-autodiscovery-f182fa99/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)