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VERITY Conversational Fact-Checker
x402
VERITY Conversational Fact-Checker is a paid API for AI agents from verity.basechainlabs.com, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-14).
Checks a claim's factual status and returns a verdict (CURRENT/OUTDATED/DISPUTED/UNVERIFIABLE) with confidence score and sources, with persistent memory to skip re-checking previously verified claims across sessions.
Price / call$0.1
Success—
StatusUnknown
How this service works
Conversational fact-checking with persistent memory — VERITY remembers what your agent has checked across sessions, skipping repeat lookups. Returns CURRENT/OUTDATED/DISPUTED/UNVERIFIABLE verdicts with confidence scores and sources. 0.10 USDC/call.
Output
Returns one of four verdicts — CURRENT, OUTDATED, DISPUTED, or UNVERIFIABLE — along with a confidence score (0–1), cited sources, and a summary of what has changed if the claim is outdated. If this claim was previously checked in a prior session, returns the cached result immediately to save tokens.
Example use cases
Example prompt
“Can you fact-check this claim for me: 'The global average temperature has risen by 1.5°C since pre-industrial times' — I need to know if it's current, outdated, or disputed, along with your confidence level and the sources you used?”
Technical details
Endpoint
POSThttps://verity.basechainlabs.com/api/agentWhen to prefer
Choose VERITY when your agent needs structured fact-checking verdicts with source citations and must avoid redundant API calls across multi-session workflows. The persistent memory feature is especially valuable for agents that repeatedly check overlapping claims. Prefer over generic search when you need a structured CURRENT/OUTDATED/DISPUTED/UNVERIFIABLE verdict with confidence scores rather than raw search results.
Side effects
- Claim is too vague or ambiguous to verify — returns UNVERIFIABLE with low confidence
- Claim references very recent events not yet indexed — may return UNVERIFIABLE or stale sources
- Payment not received or insufficient USDC — request rejected
- Network timeout or service unavailable — HTTP 5xx
- Claim previously checked returns stale cached result if underlying facts have changed since last session check
Input
{
"claim": "Water boils at 100 degrees Celsius at sea level",
"context": "Physics and chemistry fact",
"priority": "standard"
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
{
"status": "completed",
"tokens": 14954,
"artifact": {
"index": 0,
"parts": [
{
"text": "All sources are in strong agreement. Here is the full verification report:\n\n```json\n{\n \"verdict\": \"CURRENT\",\n \"confidence\": 95,\n \"summary\": \"The claim that water boils at 100°C (212°F) at sea level is a well-established scientific fact, confirmed unanimously across all sources consulted. This is true specifically under standard atmospheric pressure of 1 atm (101.325 kPa), which is the condition found at sea level. Wikipedia, EBSCO Research Starters, University of Maryland chemistry resources, and multiple corroborating web sources all confirm this. It is worth noting the important nuance that the boiling point of water is pressure-dependent: at higher altitudes (lower atmospheric pressure), water boils at temperatures below 100°C, and under increased pressure, it boils above 100°C. No corrections, retractions, or contradictions to this claim were found.\",\n \"what_changed\": null,\n \"sources\": [\n {\n \"url\": \"https://en.wikipedia.org/wiki/Boiling_point\",\n \"title\": \"Boiling Point — Wikipedia\",\n \"published_date\": \"2026-06-10\",\n \"source_type\": \"wikipedia\",\n \"credibility_tier\": 1,\n \"supports\": \"CONFIRMS\"\n },\n {\n \"url\": \"https://www.ebsco.com/research-starters/science/boiling-points\",\n \"title\": \"Boiling Points | Science | Research Starters — EBSCO\",\n \"published_date\": null,\n \"source_type\": \"web\",\n \"credibility_tier\": 2,\n \"supports\": \"CONFIRMS\"\n },\n {\n \"url\": \"https://terpconnect.umd.edu/~wbreslyn/chemistry/pressure/boiling-point.html\",\n \"title\": \"Boiling Point — University of Maryland\",\n \"published_date\": null,\n \"source_type\": \"web\",\n \"credibility_tier\": 1,\n \"supports\": \"CONFIRMS\"\n },\n {\n \"url\": \"https://www.compoundchem.com/2016/03/22/boiling-point\",\n \"title\": \"What Temperature Does Water Boil At? Boiling Point & Elevation — CompoundChem\",\n \"published_date\": \"2016-03-22\",\n \"source_type\": \"web\",\n \"credibility_tier\": 2,\n \"supports\": \"CONFIRMS\"\n },\n {\n \"url\": \"https://brainly.com/question/39366691\",\n \"title\": \"Water boils at 100 degrees Celsius at sea level — Brainly\",\n \"published_date\": null,\n \"source_type\": \"web\",\n \"credibility_tier\": 3,\n \"supports\": \"CONFIRMS\"\n }\n ],\n \"tools_used\": [\"retrieveCallerMemory\", \"lookupWikipedia\", \"searchClaim\", \"checkAcademic\", \"searchForUpdates\"],\n \"checked_at\": \"2025-07-17T00:00:00Z\",\n \"recommendation\": \"Accept this claim as accurate, but note the key caveat: 100°C is only the boiling point at standard sea-level atmospheric pressure (1 atm) — altitude, dissolved solutes, and pressure changes will all shift this value.\"\n}\n```\n\n---\n\n### 🟢 VERDICT: CURRENT — Confidence: 95/100\n\n**Bottom line:** ✅ The claim is **accurate and well-established**. Water boils at exactly **100°C (212°F) at sea level** under standard atmospheric pressure (1 atm / 101.325 kPa). This is confirmed by Wikipedia, a University of Maryland (.edu) source, EBSCO Research Starters, and multiple additional corroborating sources with zero contradictions found.\n\n**⚠️ Key nuance to keep in mind:**\n| Condition | Boiling Point |\n|---|---|\n| Sea level (1 atm) | **100°C** ✅ |\n| High altitude (e.g., Denver, CO) | **< 100°C** |\n| Underground / high pressure | **> 100°C** |\n| Saltwater / dissolved solutes | **Slightly > 100°C** |\n\nThe boiling point of water is **pressure-dependent**, so the claim is precisely true *only* at sea level — which is exactly what the claim states.",
"type": "text"
}
]
},
"tool_calls": [
"retrieveCallerMemory",
"lookupWikipedia",
"searchClaim",
"checkAcademic",
"searchForUpdates"
]
}Tags
x402
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