x402 endpoint delivery map -- method

Measured 2026-09-06T20:05Z to 2026-09-06T20:28Z on Base. USDC.

1. Source list: the agentic.market catalog pull of 2026-09-06, 29,364 unique endpoint URLs.
2. Selection: endpoints with at least 2 unique payers in 30 days, a catalog price above 0 and at
   or below $0.50, non-zero traffic in 30 days, and enough parameter examples in the catalog to
   build a request. Taken in descending call volume until an $8.00 budget was exhausted, plus five
   endpoints priced between $0.50 and $1.00 taken in descending claimed revenue within that band.
   This is NOT the 464 highest-traffic endpoints in the catalog: 397 of these 464 are in the
   catalog's top 464 by call volume, and the price ceiling excludes high-ticket endpoints entirely.

   SURVIVORSHIP. Read this before drawing any conclusion about how often endpoints deliver. The
   selection requires at least 2 distinct payers in the prior 30 days, which only 3,668 of 29,364
   catalogued endpoints meet (12.5%). Endpoints that take money and return nothing do not accumulate
   repeat payers, so they are largely absent from this sample by construction. Any delivery rate
   computed from these rows describes endpoints that already had customers, not endpoints in general.

   The single largest traffic source in the catalog is excluded by these filters:
   agents.chain.link, 52,500 calls in 30 days across 4 endpoints, 17.7% of all catalogued call
   volume, dropped because its endpoints report only 1 unique payer.
3. Each endpoint was requested once WITHOUT payment. That is free and returns the 402 terms.
4. Where the quoted Base USDC price was at or below $1.00 and within 5% of the catalog price, the
   endpoint was then paid once, and the response recorded verbatim.
5. Requests were built from the catalog's own parameter examples. Some of those examples are
   placeholders such as the literal string "string", so some responses are rejections of a
   malformed request rather than a judgement on the endpoint.
6. Total spent: $5.58.

Known limits, stated plainly:
- One measurement, one day, one chain. No claim about consistency over time.
- 464 of 29,364 endpoints. The $0.50 price ceiling means no high-ticket endpoint was tested.
- One call per endpoint. This shows whether an endpoint delivered once, not whether it is reliable.
- response_chars counts UTF-16 code units, not bytes; non-ASCII responses are undercounted.
- Three endpoints were paid twice (once in a smoke test, once in the main run).
- 32 paid requests recorded no HTTP status, having failed before a response was parsed.

Reproduce: scripts/select_probe_sample.py, tools/probe/probe.mjs, scripts/build_dataset.py.