Your x402/MCP endpoint may be listed but not actually callable.

The Marketplace Visibility Audit is a structured visibility check that answers the question every x402/MCP seller eventually asks: "why is nobody finding or paying my endpoint?" Private beta. First-pass audit is free on request.

The visibility problem (in numbers)

The Decixa State of x402 report (April 2026) probed the public x402 ecosystem and surfaced a structural quality gap: most endpoints that claim to be x402 do not actually return a valid 402 handshake when an agent tries to call them. The numbers below are from that independently-published report:

Source: Decixa, State of x402, April 2026 — primary ecosystem quality data. LION did not run the probes; LION is building tooling that helps individual sellers diagnose and fix the gaps the report describes.

Who this is for

• x402 sellers who think they are listed somewhere (x402scan, awesome-x402, MCP Registry, Coinbase Bazaar, Glama, Skiln) but see no agent calls.
• MCP server operators who registered their server but cannot tell whether agents are actually able to discover and pay it.
• Agent storefront owners who recently rotated their payTo address and want to confirm registries reflect the change.
• Builders who shipped an x402 endpoint and want an independent second pair of eyes on its discovery surface before announcing it.

What the audit checks

Sample audit output (JSON)

Output schema is stable. Optional fields are returned as null when the audit cannot quantify them — the audit does not invent values.

Why these checks

A buyer agent that wants to call an x402 endpoint does roughly this:

1. Discover the endpoint (via x402scan, Coinbase Bazaar, MCP Registry, llms.txt, openapi.json).
2. Fetch the paid URL and read the 402 body to learn price, asset, payTo, network, scheme.
3. Sign a payment over the advertised terms.
4. Retry with the signed payment and expect a 200.

If any step in that chain has a leak — registry stale, 402 body malformed, payTo drift, machine-discovery file missing — the agent silently moves on. The audit is just a structured way to find which step has the leak on a given endpoint, before that endpoint loses any more agent traffic.

Price hypothesis

The $0.05 price is a working hypothesis, not a committed live price. The paid route is built but not yet advertised publicly — first we want to confirm via free first-pass audits that the output is actually useful to real sellers.

What this audit is not

• It is not a discovery registry. x402scan, Coinbase Bazaar, and the MCP Registry already do that. The audit just checks whether your existing listings are healthy and complete.
• It is not a security audit of your code. SSRF, prompt injection, or business-logic vulnerabilities are out of scope. The audit only looks at the public discovery and payment surface.
• It is not a recommendation to use any specific facilitator, marketplace, or chain. The audit reports what is observable; the seller decides what to fix.
• It is not a paid promotion. LION does not custody funds, does not move funds, does not sign transactions on the seller's behalf, and does not auto-publish anywhere.

Request a free first-pass audit

During the private beta, LION will run a free first-pass visibility audit against any public x402 or MCP endpoint, on request. The output is the same JSON shape shown above. No account, no API key, no payment.

Free first-pass audit slots during private beta are limited by manual review — expect a one-business-day turnaround.

Machine-readable agent metadata

When the paid route launches publicly, this page will be updated with the canonical paid URL, the canonical payTo, and a public 402 example. Until then, request a free first-pass audit via the email link above.

Build: LION_MARKETPLACE_VISIBILITY_AUDIT_SPEC_PAGE_001=2026_05_27_CTA_FIX