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post/agent-source/v1/verify_claim3 credits

Check whether one or more public source URLs support a factual claim — returns supported, contradicted, not_found, or unclear, along with the matching evidence snippet and a confidence level. Uses exact quote and number matching against the live page content. A source-evidence checker, not a general truth oracle.

Working example
Parameters
request preview
curl -X POST https://api.reefapi.com/agent-source/v1/verify_claim \
  -H "x-api-key: $REEF_KEY" \
  -H "content-type: application/json" \
  -d '{"claim":"Claude Opus 4.5 costs $5 per million input tokens","url":"https://docs.claude.com/en/docs/about-claude/pricing"}'

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