The oldest objection to buying data is that you can’t see it before you pay — and once you’ve paid, you own the disappointment. A marketplace for agents has to kill that objection mechanically, because an agent burned once is a workflow that never buys again.
Here’s the evaluation stack every datapoint.market listing exposes, in order of increasing certainty — all of it free, none of it requiring an account.
1. The feed: judge fit without a single call
/discover.json carries every
public listing with price, networks, response schema, license, file size,
delivery type, and join card inline. An agent can
shortlist candidates — right shape, right key, right price — before touching
any endpoint.
2. The sample: real structure, protected values
Every listing shows a sample with three declared axes:
- protection —
synthetic(default: the structure is real, values are fabricated),redacted, orreal; - provenance —
live(captured by actually calling the origin),declared, ormcp_introspected; - freshness — is the sample within its refresh window?
Synthetic-by-default cuts both ways, deliberately: sellers can list without leaking a row of real data, and buyers know exactly what kind of evidence they’re looking at. Read the schema, not the fabricated values.
3. The join card: will it connect to what you have?
The card declares what one record represents and which columns are join
handles, in the seller’s own words, verified against the schema. It’s the
difference between “looks relevant” and “joins on domain, lowercase,
no www” — fusion planned before paying.
4. Free trials: real data, metered
Some listings offer free trial calls — a few real (unpaid) requests,
metered per account. No special tool: call_endpoint with no payment either
returns trial data or a price quote. It is impossible to spend by accident
while evaluating.
5. The quote: the exact price, cryptographically specific
quote_endpoint returns the x402 payment requirements — price, network,
pay-to — for the call you’re about to make. Nothing is discovered at
checkout, because there is no checkout.
6. Trust signals from actual behavior
Listings carry a ✓ verified badge only when they served fresh data to a real paying buyer recently; reliability stats (success rate, latency) are computed from actual paid traffic, not seller claims. ▣ DS-ready marks complete listings (description, per-column codebook, sample rows, license); ⧉ Fusion-ready marks verified join cards.
The decision, with zero spend
Shortlist from the feed → check the schema and card → trial if offered → quote → then pay, with a budget-capped wallet and an on-chain receipt. The first dollar moves after the evaluation is done, not before. If what you need isn’t there, say so — zero-result searches are logged, and vendors build against the board.
Guides: buying with the connector · data samples & trials, in depth