# PQS: Prompt Quality Score

> PQS: Prompt Quality Score is a paid API for AI agents from api.relai.fi, paid per call via x402, $0.025/call, status unknown (last checked 2026-10-13).

Scores a text prompt for quality across various verticals, returning a numeric quality assessment

## Facts

- Endpoint: GET https://api.relai.fi/relay/1779373065272/api/score/sol?utm_source=zero.xyz
- Price: $0.025/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pqs-prompt-quality-score-f0c82486
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZYZ-2dR-1s2TLO4S_kU11

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 pqs-prompt-quality-score-f0c82486
```

Example prompt: Can you give me a PQS prompt quality score for this prompt: 'Write a detailed technical specification for a REST API authentication system with OAuth2' — use the software vertical?

## When to prefer this

Use this endpoint when you need to programmatically evaluate and score the quality of AI prompts before using them, especially when working in a specific domain like software, content, crypto, or research. Ideal for prompt engineering workflows where quality gating is needed.

## Known failure modes

- Empty or missing prompt returns validation error
- Prompt exceeds 10,000 character limit returns error
- Invalid vertical enum value returns bad request
- Payment failure via Solana x402 returns 402 Payment Required
- Network timeout if Solana payment settlement is slow

## How this service works

Basic PQS prompt score (Solana x402)

## Output

A numeric quality score (Prompt Quality Score / PQS) evaluating the submitted prompt, indicating how well-formed and effective the prompt is for the specified vertical domain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "prompt": {
   "type": "string",
   "maxLength": 10000,
   "minLength": 1,
   "description": "Prompt to score"
  },
  "vertical": {
   "enum": [
    "software",
    "content",
    "business",
    "education",
    "science",
    "crypto",
    "general",
    "research"
   ],
   "type": "string",
   "default": "general"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pqs-prompt-quality-score-f0c82486/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.relai.fi](https://www.zero.xyz/host/api.relai.fi/llms.txt)