# 8k4 Protocol — ERC-8004 Agent Trust Score Explanation

> 8k4 Protocol — ERC-8004 Agent Trust Score Explanation is a paid API for AI agents from api.8k4protocol.com, paid per call via x402, $0.001/call, status down (last checked 2026-09-15).

Returns a human-readable explanation of an ERC-8004 agent's trust score, including specific positive factors and cautions that contributed to the score.

## Facts

- Endpoint: GET https://api.8k4protocol.com/agents/%7Bagent_id%7D/score/explain
- Price: $0.001/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-erc-8004-agent-trust-score-explanation-79dbdbcf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XooURko299lV_gkdSSTBK

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-erc-8004-agent-trust-score-explanation-79dbdbcf
```

Example prompt: Can you explain why agent 21480 on the Base chain has a trust score of 78.4 — specifically what positives and cautions are affecting its ERC-8004 rating right now?

## When to prefer this

Use this endpoint when you need to understand the reasoning behind an ERC-8004 agent's trust score — not just the numeric value but the specific factors driving it. Prefer this over the raw score endpoint when you need to communicate trust decisions to users, audit agent risk, or debug why an agent is rated a certain way. This is the explainability layer on top of the score.

## Known failure modes

- Unknown agent_id returns 404 with agent not found error
- Invalid chain identifier returns 400 bad request
- Agent has no score yet returns empty or unscored response
- Expired or missing x402 payment header returns 402 Payment Required
- Rate limiting exceeded returns 429 Too Many Requests

## How this service works

Get score explanation with positives and cautions

## Output

A JSON object containing the agent's numeric trust score, risk band (e.g. MEDIUM), confidence tier, a list of positive factors (e.g. 'Verified wallet activity'), a list of cautions (e.g. 'Sparse validator history'), the global EIP-155 agent ID, the chain, and the timestamp of the score calculation.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "as_of": "2026-03-03T00:00:00+00:00",
  "chain": "base",
  "score": 78.4,
  "agent_id": 21480,
  "cautions": [
   "Sparse validator history"
  ],
  "global_id": "eip155:8453:0x8004...:21480",
  "positives": [
   "Verified wallet activity"
  ],
  "risk_band": "MEDIUM",
  "confidence_tier": "MEDIUM"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/8k4-protocol-erc-8004-agent-trust-score-explanation-79dbdbcf/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)