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X402 Delivery Size Check
x402
X402 Delivery Size Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).
Checks whether a serialized agent result's byte size falls within a buyer-specified maximum, returning acceptance or rejection status with mismatch reasons.
Price / call$0.001
Success—
StatusUnknown
How this service works
X402 Delivery Size Check: X402 Delivery Size Check checks serialized result byte size against a buyer limit from bounded caller-supplied values without an external provider. Call X402 Delivery Size Check before paying for or accepting an x402 or agent delivery assembled from caller-supplied challenge and result metadata. Returns contract-specific checks, normalized evidence, mismatch reasons, and an explicit acceptance or rejection status for X402 Delivery Size Check as versioned deterministic…
Output
Returns an explicit acceptance or rejection status, the measured byte size of the serialized result, any mismatch reasons explaining why the limit was exceeded, and normalized evidence — all computed deterministically in memory without external calls or data retention.
Example use cases
Pre-payment x402 size gate
“Before settling this x402 payment, check that the result I got back fits within 8192 bytes — show me whether it passes or fails and any mismatch details.”
Agentic marketplace buyer protection
“I'm a buyer on an agent marketplace and just received a result; can you verify the serialized payload doesn't exceed my contracted 5000-byte maximum before I approve the transaction?”
Delivery budget enforcement for agent fleet
“Our agent fleet has a 20000-byte delivery cap per result — run this result object through a size check and tell me if it's within budget or why it would be rejected.”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/x402-delivery-size-checkWhen to prefer
Use this endpoint when you need a deterministic, in-memory byte-size check against a buyer-specified limit before accepting or paying for an x402 or agentic marketplace delivery. Prefer it over custom client-side size checks when you need a normalized, versioned evidence record and explicit acceptance/rejection reasoning suitable for dispute resolution or audit trails.
Side effects
- Result object has more than 128 properties (maxProperties exceeded), causing a validation error
- maximum_bytes not provided or non-integer, returning a parameter error
- Result cannot be serialized (circular references or non-serializable values), causing a processing error
- Byte size exactly at boundary may return edge-case acceptance depending on comparison operator semantics
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| result | object | Result supplied to X402 Delivery Size Check; used only for this bounded calculation and processed in memory without retention. |
| maximum_bytes | integer | Maximum Bytes supplied to X402 Delivery Size Check; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"bytes": 39,
"within_budget": true
},
"schema": "delx/util-x402-delivery-size-check/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "076621b47df3f39c3106d66269581bbf20cc78094ab64cec4fdb10ac2b5f03d1",
"external_calls": 0
},
"operation": "delivery_contract:x402_delivery_size_check"
}
}Tags
x402
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