Ontario Protocol.
x402 pre-payment decision playbook

Validate the x402 manifest for MCP tool builders

The service needs discoverable metadata that agrees with live endpoint behavior. This playbook maps the decision to observable Ontario evidence so an agent can fail closed before payment.

Search Console priority Validate manifest MCP builders No-payment first
Decision question: Can MCP tool builders rely on this x402 endpoint without paid tools that agents cannot inspect before invocation?

Only after MCP tool builders can inspect accepts entries, methods, network, asset, price format, facilitator metadata, and freshness. If the evidence is missing, stale, or contradictory, the agent should fail closed.

Required evidence

  • Confirm the endpoint maps to a real payment resource for builders exposing paid MCP tools or HTTP tools to agent runtimes.
  • Require accepts entries, methods, network, asset, price format, facilitator metadata, and freshness.
  • Reject when there is missing accepts entries, stale metadata, invalid price format, or network mismatch.
  • Link the final decision to a public report, manifest, benchmark row, or policy outcome.

Reject conditions

Reject or send to human review when there is missing accepts entries, stale metadata, invalid price format, or network mismatch.

Do not let a positive-looking badge or directory row override a stale or contradictory live check.

Agent workflow

  1. Start with the no-payment evidence path.
  2. Run the Ontario verifier or policy endpoint shown below.
  3. Compare live endpoint behavior against manifest and discovery metadata.
  4. Store the report_id or policy decision with the agent's payment log.
  5. Send the payment only when the agent's own policy allows it.

Command or probe

curl https://example.com/.well-known/x402.json
# Compare manifest network, asset, resource, and price against the live 402 challenge.

Primary Ontario surface: /.well-known/x402.json

Sourceability note

Manifest quality is part of Ontario readiness and discovery scoring.

KPI: more paid tools with machine-readable verification metadata.

Trust boundary

Ontario Protocol provides readiness and trust signals based on observable endpoint behavior, manifest metadata, payment challenge behavior, report history, and public evidence. It does not guarantee endpoint safety, service quality, financial outcome, or future behavior.

Open the manifest validator answer Run verifier Browse discovery Read trust boundary