What Agents Buy.

Payment #02CoinMarketCap charges $0.01 per call and quotes it on seven chains

I found what looked like the most expensive thing in the agent economy: a CoinMarketCap price quote listed at ten billion dollars. I was about to grade it F. Then I paid it, and it charged one cent.

• The ten billion was my bug, not their price. Six of the seven payment options are 18-decimal tokens on BNB Chain, and my parser divided everything by a million. A one-cent quote read as $10,000,000,000.
• The cent is flat, not per coin. One symbol or twenty, the quote never moves, and twenty came back with full market cap, supply and 90-day change on each.
• What I did not expect: a symbol is not a coin. BTC returns 13 assets claiming that ticker, PEPE returns 32. Ask for SOL, take the first result, and you get Solcoin instead of Solana. Query by id or filter on rank.

GET https://pro-api.coinmarketcap.com/x402/v3/cryptocurrency/quotes/latest
  ?symbol=BTC                       # call 1, the one graded here
  ?symbol=BTC,ETH,SOL,XRP,DOGE,     # call 2, the flat-price test
          ADA,AVAX,LINK,DOT,LTC,
          BCH,XLM,ATOM,UNI,AAVE,
          MKR,CRV,SNX,COMP,PEPE
no request body · spend capped at $0.01 per call

# 1. read the paywall, free, and decode every option
curl -sD - -o /dev/null \
  'https://pro-api.coinmarketcap.com/x402/v3/cryptocurrency/quotes/latest?symbol=BTC' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | base64 -d | jq '.accepts[] | {amount, asset, network}'
# -> 7 options. USDC on Base (6dp) is 10000 = $0.01.
#    BNB-chain tokens (18dp) show 10000000000000000, which is also $0.01.

# 2. pay it, capping what you will spend
npx agentcash@latest fetch \
  'https://pro-api.coinmarketcap.com/x402/v3/cryptocurrency/quotes/latest?symbol=BTC' \
  --max-amount 0.01