# 8k4 Protocol — Upload ERC-8004 Agent Metadata

> 8k4 Protocol — Upload ERC-8004 Agent Metadata is a paid API for AI agents from api.8k4protocol.com, paid per call via x402, $0.1/call, status down (last checked 2026-09-15).

Upload signed ERC-8004 metadata for a specific agent to register or update its on-chain trust profile

## Facts

- Endpoint: POST https://api.8k4protocol.com/agents/%7Bagent_id%7D/metadata
- Price: $0.1/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/8k4-protocol-upload-erc-8004-agent-metadata-3afeee51
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zqbu0rFkccOnau1UaEcH8

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 8k4-protocol-upload-erc-8004-agent-metadata-3afeee51 -d '<json body>'
```

Example prompt: Upload the signed ERC-8004 metadata for agent ID 21480 on the Base chain to the 8k4 Protocol so it gets a trust profile URI.

## When to prefer this

Use this endpoint when you need to register or update a signed ERC-8004 metadata record for a specific AI agent on the 8k4 Protocol trust network. This is the write operation for agent metadata — use sibling endpoints for reading trust scores, score explanations, or validation history.

## Known failure modes

- Invalid or missing agent_id returns a 400 or 404 error
- Unsigned or malformed ERC-8004 metadata payload causes a validation rejection
- Signature verification failure returns an authorization error
- Duplicate metadata upload for same agent may conflict or overwrite depending on protocol rules
- Payment of 0.1 USDC not received results in x402 payment required error
- Unsupported chain identifier causes a chain resolution error

## How this service works

Upload signed ERC-8004 metadata

## Output

Returns a JSON object containing the metadata URI where the agent's metadata is now hosted (e.g. https://api.8k4protocol.com/metadata/base/21480.json), the chain name (e.g. 'base'), and the agent_id that was registered.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "uri": "https://api.8k4protocol.com/metadata/base/21480.json",
  "chain": "base",
  "agent_id": 21480
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/8k4-protocol-upload-erc-8004-agent-metadata-3afeee51/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.8k4protocol.com](https://www.zero.xyz/host/api.8k4protocol.com/llms.txt)