# Cited Brief

> Cited Brief is a paid API for AI agents from cited-brief.cited-brief.workers.dev, paid per call via x402, $0.1/call, status unknown (last checked 2026-10-17).

Answers a user question by extracting and citing evidence from specified web pages, returning a verified answer with source quotes

## Facts

- Endpoint: POST https://cited-brief.cited-brief.workers.dev/brief?utm_source=zero.xyz
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cited-brief-39455905
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_oPceLxD1VmT8_orybHw3g

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 cited-brief-39455905 -d '<json body>'
```

Example prompt: Go to https://stripe.com/pricing and https://stripe.com/docs/billing and answer: what does Stripe charge per successful card transaction for standard accounts?

## When to prefer this

Choose this endpoint when you need a grounded, citation-backed answer derived from specific known URLs rather than a broad web search. It is ideal when you already know which pages contain the answer and want verifiable quotes — not open-ended discovery. Prefer it over general search APIs when auditability and source traceability matter, and over raw scraping when you need a synthesized answer rather than raw HTML. The pay-per-call USDC model makes it suitable for on-demand agent workflows without subscriptions.

## Known failure modes

- URL is behind a paywall or login — page content cannot be fetched, claim dropped
- URL returns non-HTML content (PDF, binary) — may fail to extract text
- Question exceeds 500 characters — request rejected with validation error
- Fewer than 1 or more than 5 URLs provided — request rejected
- No verifiable evidence found in pages — answer returned with zero claims
- Page loads slowly or times out — dropped from evidence set
- USDC payment insufficient or x402 handshake fails — payment error, call not executed

## How this service works

Pay-per-call web research tools for AI agents, paid in USDC over x402.

## Output

A JSON object containing a plain-language answer to the question, an array of claims each with the source URL, the verbatim quote used, and the supporting text, plus a count of claims dropped for being unverifiable and the model that generated the answer.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "urls": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 5,
   "minItems": 1,
   "description": "Public http(s) pages to answer from"
  },
  "question": {
   "type": "string",
   "maxLength": 500,
   "minLength": 1,
   "description": "The question to answer"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "model": "gemini-3.5-flash-lite",
  "answer": "The Pro plan costs $10 per user per month when billed yearly.",
  "claims": [
   {
    "url": "https://example.com/pricing",
    "text": "Pro is $10 per user per month, billed yearly",
    "quote": "Pro $10 per user/month billed annually"
   }
  ],
  "question": "What does the Pro plan cost per user per month, billed yearly?",
  "dropped_unverified": 0
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cited-brief-39455905/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from cited-brief.cited-brief.workers.dev](https://www.zero.xyz/host/cited-brief.cited-brief.workers.dev/llms.txt)