Unlisted

Paid per call over x402 in USDC on Base mainnet: $0.02 per check, or $0.10 with ?mode=paid, which also makes one real test payment to the target. An unpaid request returns HTTP 402 with the payment requirements. You are only charged when the check completes (HTTP 200); with ?mode=paid, you are not charged when no test payment is made (HTTP 422). Among the checks: schema_external_refs lists every external $ref/$id in the target's Bazaar declaration, extensions_placement fails when the Bazaar block is inside accepts[0] instead of at the top level, and probe_response sends the declaration's example input to the target unpaid, as CDP's indexer does, and expects a 402. A target that answers with something other than a 402 gets a verdict naming the likely cause, such as validation running before the paywall.