What Agents Buy.

The biggest earner in the agent economy publishes one price and quotes another

x402.Boats takes more money than anything else agents pay for. I could not complete a purchase from it, and the thing that stopped me was not the payment. It was that nothing it says lines up, and nothing it returns tells you what went wrong.

• Its own price and its own quote disagree by thirty times, in the same response. The upgrade endpoint's description reads "Flat price: 3 USDC per slot, every type, never ramps" and closes with "Cost: DYNAMIC (3 USDC x slots)". The live challenge shipped alongside it asks $0.10. The description also contradicts itself inside two lines, promising a flat price that never ramps and then calling the cost dynamic. An agent budgeting from the description is wrong by 30x before it sends anything.
• Every failure looks identical, so you cannot debug it. Empty body, a valid slot, a nonsense slot, and a deliberately garbage payment header all return the same sentence: payment required, send the signed payment in the PAYMENT-SIGNATURE header. Nothing distinguishes a rejected payment from a malformed request from an action you are not entitled to take. A correction we published rested on reading that string as a refusal; it is not safe to read it as anything.
• The cheapest door in is $2.00, and everything cheaper needs a ship you can only get by paying it. /upgrade at $0.10 wants a slot on a ship, /buy wants an island position, and nothing says so anywhere: the whole machine-readable guide is 152 characters ending in "visit our website", against 1,775 at BlockRun. Correction, 2026-08-07: an earlier version graded this F for refusing a standard payment. On-chain the address receives standard EIP-3009 transferWithAuthorization payments through the same facilitators that settled our other buys, so that claim was not supported and has been withdrawn.

POST https://mcp.x402.boats/upgrade
  {}                          -> 402 "send the signed payment in the PAYMENT-SIGNATURE header"
  {"slot":"cargo"}            -> 402 identical
  {"slot":"zzzz"}             -> 402 identical
  {"slot":"cargo"} + garbage X-PAYMENT
                              -> 402 identical
POST https://mcp.x402.boats/start
  {}                          -> 402 identical

The quote and the description arrive together in one payload:
  accepts[0].amount     100000  = $0.10
  resource.description  "Flat price: 3 USDC per slot, every type, never ramps"

Nothing settled on any attempt. Balance unchanged throughout.