buy_observation
Purchase a signed observation from an independent party to verify a URL's availability or a transaction's settlement, yielding evidence usable for corroboration.
Instructions
Purpose: have a disinterested third party go and look at something, then sign what it saw — whether a URL was still answering hours later, or what the chain actually says about a settlement. The signed observation is evidence from someone who is not you and not the party being checked, which is the whole point: a self-report cannot do this job. Use when an agent needs its own claim, or a counterparty's, corroborated by an outside observer.
Items on this shelf (pass one as item_id):
phantom_check: Phantom Check, $0.25 fixed, instant. A signed observation of the named URL, made out-of-band about six hours after purchase.
settlement_attestation: Settlement Attestation, $0.004 fixed, instant. A signed JSON observation of one Base transaction — status (SETTLED, NOT_FOUND, PENDING_FINALITY, INSUFFICIENT_MATCH or REVERTED), block height, confirmations, chain head, the query echoed back, and an evidence hash — verifiable against the store's published key without asking the store. Instant.
Pass item_id to choose. instant items complete in one call, the result carrying deliverable, cert_id and patron_number. Payment rides x402 in _meta['x402/payment']; without it this tool returns error 402 with the payment requirements in error.data. A bare stocked shelf or a shuttered human shelf refuses honestly BEFORE payment terms are issued. Retries are safe with _meta['x402/idempotency-key'] (16-128 chars, keep it secret): repeating the same key for the same item and payer within 24h returns the original result with no second charge. Guaranteed: signature validity forever; verification free forever; price as displayed; delivery format as specified. Not guaranteed: fitness for your particular task; future protocol compatibility beyond stated interfaces; human-labor turnaround faster than posted SLA. Retrying? A second call is a second charge UNLESS you echo the idempotency.suggested_key from the 402 back as _meta['x402/idempotency-key'] — then a retry inside the minute returns your original purchase, uncharged.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| url | No | The http(s) URL the store walks past ~6 hours from now. | |
| item_id | Yes | Which item on this shelf to buy. Required. Each item's own required fields are listed in this schema's allOf branches and in the description above. | |
| agent_name | No | Optional name for the certificate and badge. |
Output Schema
| Name | Required | Description | Default |
|---|---|---|---|
| cert_id | Yes | The signed certificate's id. | |
| message | No | The store's confirmation line. | |
| tip_usdc | No | Anything above the minimum. | |
| badge_url | No | Your patron badge, SVG. | |
| paid_usdc | No | What settled, in USDC. | |
| signature | No | ed25519 signature over the certificate. | |
| verify_url | No | Check the signature here any time, free. | |
| deliverable | No | The goods themselves, as text. Instant items. | |
| patron_number | Yes | Your sequential patron number. |