# SperaxOS ERC-8004 Agent Metadata Setter

> SperaxOS ERC-8004 Agent Metadata Setter is a paid API for AI agents from chat.sperax.io, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-20).

Sets a metadata key-value pair on an ERC-8004 registered on-chain agent NFT across supported blockchains

## Facts

- Endpoint: POST https://chat.sperax.io/api/x402/tools/erc8004/setMetadata?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/speraxos-erc-8004-agent-metadata-setter-3b6e34bd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_G1CHYAtSK19VeLbcciwKJ

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-metadata-setter-3b6e34bd -d '<json body>'
```

Example prompt: Set the metadata key 'a2a.endpoint' to 'https://myagent.example.com/a2a' on my ERC-8004 agent with token ID 42 on BSC mainnet.

## When to prefer this

Use this endpoint when you need to write or update structured metadata fields on an ERC-8004 compliant agent NFT on a supported EVM chain. It is the right choice when configuring agent discovery properties (a2a.endpoint, mcp.endpoint, x402.enabled), linking identity documents (DID, ENS), or setting versioning metadata — especially within the SperaxOS / agentcash ecosystem where no traditional API key is required and payment is handled via x402 micropayments.

## Known failure modes

- Invalid or non-existent agent token ID returns an error indicating the agent cannot be found
- Unsupported chain value causes a validation error listing accepted options
- Empty or missing key/value fields result in a schema validation error
- Caller wallet does not own or have permission to update the specified agent NFT
- Blockchain network congestion or RPC failure causes a transaction timeout
- Malformed metadata value (e.g. non-UTF-8 string) may be rejected

## 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

A confirmation of the on-chain metadata update transaction, indicating that the specified key-value pair has been written to the ERC-8004 agent NFT record on the chosen blockchain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "key": {
   "type": "string",
   "description": "Metadata key (e.g., \"version\", \"a2a.endpoint\", \"mcp.endpoint\", \"did\", \"ens\", \"x402.enabled\")"
  },
  "chain": {
   "type": "string",
   "default": "bsc-testnet",
   "description": "Blockchain where the agent is registered. Options: bsc-testnet, bsc-mainnet, ethereum, sepolia"
  },
  "value": {
   "type": "string",
   "description": "Metadata value as a UTF-8 string"
  },
  "agentId": {
   "type": "number",
   "description": "The token ID of the agent to update"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/speraxos-erc-8004-agent-metadata-setter-3b6e34bd/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)