# SperaxOS ERC-8004 Agent Reputation HEAD Check

> SperaxOS ERC-8004 Agent Reputation HEAD Check is a paid API for AI agents from chat.sperax.io, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-22).

Checks the ERC-8004 reputation metadata availability for a given agent ID on the SperaxOS DeFi intelligence platform via a lightweight HEAD request, payable with USDC on Base.

## Facts

- Endpoint: HEAD https://chat.sperax.io/api/x402/v1/erc8004/reputation/%7BagentId%7D?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/speraxos-erc-8004-agent-reputation-head-check-077b0420
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NfMg00nSU9DtE38UkfYFe

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 speraxos-erc-8004-agent-reputation-head-check-077b0420 -d '<json body>'
```

Example prompt: Can you check whether the agent with ID 0xABC123 has an ERC-8004 reputation record on SperaxOS — just a quick existence check, no need to fetch the full data?

## When to prefer this

Use this endpoint when you need a fast, low-cost existence check for an agent's ERC-8004 reputation record without fetching the full payload. Ideal for pre-flight validation before deeper DeFi interactions, and preferable over a GET when you only need to confirm presence. Requires no API key — only a USDC micropayment on Base via x402.

## Known failure modes

- 404 Not Found — agent ID has no ERC-8004 reputation record registered
- 402 Payment Required — USDC payment not attached or insufficient
- 400 Bad Request — malformed agentId in the URL path
- 503 Service Unavailable — SperaxOS backend temporarily down
- Payment failure on Base network — transaction not confirmed

## How this service works

AI-powered DeFi intelligence APIs payable via the x402 HTTP payment protocol. No API key required — pay per request with USDC on Base. Identity-only (SIWX) endpoints are free for wallets with an agentcash identity.

## Output

Returns HTTP headers only (HEAD response) indicating whether an ERC-8004 reputation record exists for the specified agent ID. Status codes and headers signal availability; no response body is returned. Costs $0.001 USDC per call via x402 payment protocol.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/speraxos-erc-8004-agent-reputation-head-check-077b0420/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from chat.sperax.io](https://www.zero.xyz/host/chat.sperax.io/llms.txt)