# Cron Expression 6-Field Validator

> Cron Expression 6-Field Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-29).

Validates whether a given string is a syntactically correct 6-field cron expression

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-cron-6?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cron-expression-6-field-validator-f2a3f753
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JdTIFRJspOfevVoyape_M

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 cron-expression-6-field-validator-f2a3f753 -d '<json body>'
```

Example prompt: Can you check if '0 30 9 * * 1-5' is a valid 6-field cron expression?

## When to prefer this

Use this endpoint when you need to definitively validate a 6-field cron expression (which includes a seconds field, common in Quartz/Spring schedulers) before storing or executing it. Prefer the free sandbox endpoint POST /v1/sandbox/check-cron-6 first for development or testing; use this paid endpoint in production when sandbox is unavailable or rate-limited. Choose this over general regex checks when you need authoritative, server-side cron validation without writing your own parser.

## Known failure modes

- Empty string input returns validation error or invalid result
- String exceeding 20000 characters rejected
- Non-cron strings (plain text, 5-field cron) may return false/invalid
- Network or payment failure (x402 payment required, $0.005 USDC) causes request to fail
- Malformed JSON body returns HTTP 400

## How this service works

Call when an agent needs whether a string is a 6-field cron expression. Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/check-cron-6 first.

## Output

Returns a boolean or structured result indicating whether the input string conforms to the 6-field cron expression format, potentially including which field(s) are invalid or why the expression fails validation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."
  },
  "value": {
   "type": "string",
   "examples": [
    "0 0 * * * *"
   ],
   "maxLength": 20000,
   "minLength": 1,
   "description": "Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."
  },
  "schema": {
   "description": "JSON Schema document for schema-check SKUs. Omit it on string checks."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cron-expression-6-field-validator-f2a3f753/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)