# Verity Suite Citation & Fact-Check Endpoint

> Verity Suite Citation & Fact-Check Endpoint is a paid API for AI agents from verity-suite.onrender.com, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-15).

Searches for and returns calibrated citations that support or contradict a factual claim, returning a verdict, support score, and source list

## Facts

- Endpoint: POST https://verity-suite.onrender.com/cite
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/verity-suite-citation-fact-check-endpoint-fbd83c7d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_sff3Ao8vJqnGQ8RfAkDJ0

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 verity-suite-citation-fact-check-endpoint-fbd83c7d -d '<json body>'
```

Example prompt: Can you check whether the claim 'mRNA vaccines have been shown to reduce COVID-19 hospitalization rates by over 90%' is actually supported by real sources? Focus the search on clinical evidence.

## When to prefer this

Use this endpoint when an AI agent needs to back a specific factual claim with real, retrieved citations before presenting it to a user, publishing content, or making a decision — especially when a calibrated support score and explicit rejection reasoning are required. Prefer this over generic web search when you need a structured, fail-closed verdict with traceable sources rather than raw search results.

## Known failure modes

- No supporting sources found — returns verdict 'no_sources_found' with empty citations and support score near 0
- Claim is contradicted by retrieved sources — returns verdict 'contradicted' with reasons explaining the contradiction
- Ambiguous or overly broad statement returns 'partially_supported' with low support score and caveats
- Domain hint does not narrow results effectively, returning off-topic or low-quality sources that are rejected
- Payment not processed — call rejected before execution

## How this service works

The trust fabric for AI agents — calibrated, fail-closed services agents pay per call.

## Output

Returns a verdict enum (supported, partially_supported, no_sources_found, or contradicted), a calibrated support score from 0 to 1, a list of specific citations retrieved that bear on the statement, concrete reasons for the verdict, and optional caveats about scope limits, conflicting evidence, or recency concerns.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "statement"
 ],
 "properties": {
  "statement": {
   "type": "string",
   "description": "the factual claim to find supporting sources for"
  },
  "domain_hint": {
   "type": "string",
   "description": "optional topic/field to focus the search (e.g. 'clinical', 'tax law')"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "title": "citation_out",
 "required": [
  "verdict",
  "support",
  "citations",
  "reasons"
 ],
 "properties": {
  "caveats": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "title": "Caveats",
   "description": "scope limits, partial coverage, conflicting evidence, or recency/quality concerns the caller should know"
  },
  "reasons": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "title": "Reasons",
   "description": "concrete grounds for the verdict, including why any candidate sources were rejected (off-topic, unverifiable, low-quality, vague, contradicts)"
  },
  "support": {
   "type": "number",
   "title": "Support",
   "maximum": 1,
   "minimum": 0,
   "description": "calibrated 0..1: how strongly the retrieved sources actually establish the statement (0=none retrieved or contradicted, ~0.3-0.7=partial, 0.8-1.0=explicit and on-point)"
  },
  "verdict": {
   "enum": [
    "supported",
    "partially_supported",
    "no_sources_found",
    "contradicted"
   ],
   "type": "string",
   "title": "Verdict",
   "description": "whether real retrieved sources actually support the statement; no_sources_found is the safe/uncertain value"
  },
  "citations": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "title": "Citations",
   "description": "only sources actually retrieved this call and verified to bear on the statement; each entry = source identifier/title + what specifically it supports. Empty if none qualify."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/verity-suite-citation-fact-check-endpoint-fbd83c7d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from verity-suite.onrender.com](https://www.zero.xyz/host/verity-suite.onrender.com/llms.txt)