# X402 Amount Budget Check

> X402 Amount Budget Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Validates a raw payment amount against a caller-supplied maximum budget, returning an explicit accept/reject decision with mismatch reasoning for x402 payment challenges.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/x402-amount-budget-check
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-amount-budget-check-044567e3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IoC-46h7lRMqgIFXDUCeO

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability x402-amount-budget-check-044567e3 -d '<json body>'
```

Example prompt: Before we approve this x402 payment, check whether the raw amount '1000000' is within our maximum budget of '5000000' — I need an explicit accept or reject with any mismatch reasons.

## When to prefer this

Use this endpoint when you need a deterministic, no-external-dependency check of an x402 raw payment amount against a caller-defined budget cap before authorizing a payment or accepting an agent delivery. Prefer it over ad-hoc client-side comparisons when you need structured rejection reasons, normalized evidence, and a versioned audit-ready decision rather than a simple boolean.

## Known failure modes

- Missing amount_raw or maximum_raw — endpoint requires both fields to compute a result
- Non-numeric or malformed raw strings may cause a validation error or unexpected rejection
- Values exceeding maxLength of 8192 characters will be rejected
- Network or service unavailability returning a non-200 response

## How this service works

X402 Amount Budget Check: X402 Amount Budget Check checks challenge raw amount against an exact buyer call budget from bounded caller-supplied values without an external provider. Call X402 Amount Budget 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 Amount Budget Check as versioned determin…

## Output

Returns a structured response containing: an explicit acceptance or rejection status, contract-specific validation checks, normalized evidence of the comparison, and mismatch reasons explaining why the amount was rejected (if applicable). The decision is deterministic and versioned, derived solely from the two caller-supplied raw values.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "amount_raw": {
   "type": "string",
   "maxLength": 8192,
   "description": "Amount Raw supplied to X402 Amount Budget Check; used only for this bounded calculation and processed in memory without retention."
  },
  "maximum_raw": {
   "type": "string",
   "maxLength": 8192,
   "description": "Maximum Raw supplied to X402 Amount Budget Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "amount_raw": "1000",
   "maximum_raw": "2000",
   "within_budget": true
  },
  "schema": "delx/util-x402-amount-budget-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "95ec59ab3108f4c8d18b157c563dcdebd3f620f744be1691dbc78948f24b6667",
   "external_calls": 0
  },
  "operation": "delivery_contract:x402_amount_budget_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-amount-budget-check-044567e3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)