# A2A Payment Pre-Payment Validator

> A2A Payment Pre-Payment Validator is a paid API for AI agents from agent-a2a-payment-mk77y.ondigitalocean.app, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-15).

Validates agent-to-agent USDC payment requests before execution, returning VERIFIED or FAILED with structured violation details

## Facts

- Endpoint: POST https://agent-a2a-payment-mk77y.ondigitalocean.app/verify
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/a2a-payment-pre-payment-validator-2105c2d8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5ycSOh3R0hJeVj0T3IeP9

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 a2a-payment-pre-payment-validator-2105c2d8 -d '<json body>'
```

Example prompt: Before I send the USDC payment, run a pre-payment validation on this agent-to-agent request — it's a POST with a JSON body containing the skill metadata and requested permissions — and tell me if it comes back VERIFIED or list all the violations I need to fix.

## When to prefer this

Choose this endpoint when building agent-to-agent payment pipelines that use the x402 protocol and USDC, specifically when you need structured pre-flight validation before committing a payment. It is especially useful in automated agent workflows where silent failures are costly and you need a machine-readable violations[] list to programmatically handle errors. Prefer this over ad-hoc payment submission when you want to gate execution on a VERIFIED status before spending USDC.

## Known failure modes

- Missing required 'input' object returns schema validation error
- Invalid HTTP method (not POST/PUT/PATCH) causes rejection
- Malformed body type (not json/form-data/text) triggers violation
- Insufficient or invalid requested_permissions returns FAILED with permission violations
- Network/server error on DigitalOcean host returns 5xx
- Payment proof not included causes re-validation loop — must pay 0.25 USDC then resubmit

## How this service works

a2a_payment_v1 — pre-payment validation for agent-to-agent USDC. VERIFIED or FAILED with structured violations[]. Pay Base USDC then resubmit with payment proof.

## Output

Returns a structured JSON object indicating either VERIFIED (the payment request is valid and ready to proceed) or FAILED with a violations[] array listing each specific validation error, such as missing fields, invalid permissions, or malformed body — allowing the caller to correct issues before resubmitting with payment proof.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "context": {
   "type": "object"
  },
  "skill_md": {
   "type": "string"
  },
  "requested_permissions": {
   "type": "array"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/a2a-payment-pre-payment-validator-2105c2d8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-a2a-payment-mk77y.ondigitalocean.app](https://www.zero.xyz/host/agent-a2a-payment-mk77y.ondigitalocean.app/llms.txt)