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AI Answer Hallucination Entity Checker (Wikidata)
x402
AI Answer Hallucination Entity Checker (Wikidata) is a paid API for AI agents from api.fadeandco.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-29).
Checks up to 5 capitalised named entities in an AI-generated text against Wikidata to verify their existence, returning found/not-found status, Wikidata IDs, descriptions, and sentences containing years for manual review.
Price / call$0.003
Success—
StatusUnknown
How this service works
Checks the named entities in an AI answer (up to 5 capitalised names) against Wikidata: each name is marked found or not found, with its Wikidata ID and description, and sentences containing a year are listed for review. It checks that entities exist, not that claims about them are true, so a found entity can still have a wrong fact.
Output
A JSON object listing each detected named entity with its Wikidata existence status ('found' or 'not found'), its Wikidata ID and short description when found, plus a list of sentences from the input that contain a year for human review. Also includes a timestamp, a count of not-found entities, and a note reminding that existence does not verify factual accuracy of claims.
Example use cases
LLM response quality gate
“Before I publish this AI-written bio, check whether all the named people and organisations in it actually exist — here's the text: 'Ada Lovelace worked alongside Charles Babbage at the Royal Society of London and published her famous notes in 1843.'”
RAG pipeline hallucination audit
“My RAG system generated this answer about historical figures — can you verify which of the capitalised names are real Wikidata entries and list any sentences that include years so I can review them manually? Text: 'Isaac Newton was mentored by Gottfried Leibniz at Cambridge University, publishing Principia Mathematica in 1687.'”
Chatbot output moderation
“I need to check this chatbot response for made-up entity names before showing it to users — please look up each capitalised name in Wikidata and tell me which ones aren't found: 'The treaty was signed by President Marlowe Hendricks and ratified by the United Nations in 2019.'”
Technical details
Endpoint
POSThttps://api.fadeandco.workers.dev/api/agent-intel/hallucination-claim-checker?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a lightweight, fast existence-check on named entities in an AI-generated text without running a full semantic fact-verification pipeline. It is ideal for post-generation quality gates in LLM pipelines, RAG audits, or chatbot moderation where you want to quickly surface potentially hallucinated proper nouns and flag date-bearing sentences for human review. Prefer this over general web-search fact-checkers when you specifically want structured Wikidata provenance (IDs and descriptions) for each entity.
Side effects
- Text shorter than 10 or longer than 5000 characters returns a validation error
- No capitalised names detected results in an empty entity list
- Wikidata API unavailability causes lookup failure
- Ambiguous or very common capitalised words (e.g. 'The', 'A') may not resolve to meaningful entities
- More than 5 capitalised names causes only the first 5 to be checked
- Non-English entity names may have lower Wikidata match rates
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| text | string | The model answer to check, 10 to 5000 characters |
Output
Schema · Response
{
"type": "json",
"example": {
"note": "Existence check only: a found entity can still carry a wrong date or fact. Review the sentences with years yourself.",
"source": "https://www.wikidata.org/w/api.php",
"entities": [
{
"name": "Marie Curie",
"status": "found",
"wikidataId": "Q7186",
"description": "Polish-born French physicist and chemist (1867–1934)"
},
{
"name": "Nobel Prize",
"status": "found",
"wikidataId": "Q7191",
"description": "set of annual international awards, primarily 5 established in 1895 by Alfred Nobel"
}
],
"checkedAt": "2026-10-23T09:35:21.542Z",
"notFoundCount": 0,
"sentencesWithYears": [
"Marie Curie won the Nobel Prize in 1903.",
"She later moved to Mars in 1921."
]
}
}Tags
x402
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