2 services carry this tag in their source record. Tags come from the provider, not from us — a tag is a claim about what the service does, not proof that it does it well.
Random riddle - the riddle text and its answer as separate fields, drawn from a curated pool; the response includes the pool size
One riddle by difficulty, in English or Spanish, with the answer AND the SHA-256 of the answer in lowercase. The hash is the point: an agent can check whether its guess is right without reading the solution first, which...