Preflight Check
preflight_checkIdempotent
Use preflight_check before paying for a specific tool or server call. Name the target (server, artifact, version), the operation, the advertised cost, and your policies. Get back who is paid, what is delivered, what changed, full cost, every cut taken — a signed PROCEED, PROCEED_WITH_CAUTION, BLOCKED, or UNKNOWN verdict against your policy. Envelope only: trust_report. POST the tool inputs as JSON to paid_url with an x402 v2 PAYMENT-SIGNATURE header. See https://docs.cdp.coinbase.com/x402 Paid tool — $0.25, USDC on Base or Arbitrum One. Paid URL: https://aemb.pro/v1/preflight/check.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| intent | Yes | The intended invocation: operation (required), params_summary (sha256 of canonical params), advertised_cost_usdc | |
| policy | No | Policy strings (max 20) | |
| context | No | principal_wallet + chain. Optional. | |
| dry_run | No | true = free dry-run, intercepted before the payment gate | |
| subject | Yes | The spend target: server_id (required), artifact (mcpb:// | oci:// | https://), claimed_version | |
| idempotency_key | Yes | Idempotency key: UUID v4, client-generated, one per logical request. Replaying the same key on this tool returns the original receipt — the action is not re-run, and the first request's receipt wins even if you resend different inputs. Published example keys are rejected. Keys are scoped per tool and per payer account: a key never returns another wallet's receipt. |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| how | Yes | How to pay: POST the tool inputs as JSON to paid_url with an x402 v2 PAYMENT-SIGNATURE header | |
| tool | Yes | Tool name, e.g. ping | |
| asset | Yes | Settlement asset | |
| price | Yes | Exact price, e.g. "$0.05" | |
| networks | Yes | EVM CAIP-2 network ids accepted | |
| paid_url | Yes | x402-paid HTTPS URL to POST the tool inputs to | |
| facilitator | Yes | x402 facilitator | |
| payment_required | Yes | Always true: this MCP tool is a payment pointer; the tool itself is monetized via x402. |