# Cron Expression Explainer & Validator

> Cron Expression Explainer & Validator is a paid API for AI agents from x402.agentutility.ai, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Parses a cron expression or macro into a plain-English description, validates it, buckets its frequency, and estimates runs per day

## Facts

- Endpoint: POST https://x402.agentutility.ai/cron-explain
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-agentutility-ai-8b91e80d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xOC6tgygze3EGS22Iungr

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 x402-agentutility-ai-8b91e80d -d '<json body>'
```

Example prompt: Can you explain what the cron expression '0 9 * * 1-5' means in plain English, tell me if it's valid, and estimate how many times per day it runs?

## When to prefer this

Use this endpoint when an agent or user needs to understand, validate, or summarize a cron schedule string without running code locally. Ideal for displaying human-readable schedule descriptions in UIs, confirming a cron string is syntactically correct before deploying a job, or estimating execution frequency for capacity planning.

## Known failure modes

- Invalid cron expression with wrong number of fields returns validation error and explanation of the syntax problem
- Unsupported macro returns error indicating which macros are accepted
- Ambiguous or malformed field values (e.g. out-of-range day numbers) return a validation failure with details
- Empty or null input returns a 400-level error

## How this service works

Cron expression parser. Takes a 5/6/7-field cron expression or @yearly/@monthly/@weekly/@daily/@hourly macro and returns a plain-English explanation, frequency bucket, validation result, and a runs-per-day estimate. Useful for explaining a schedule to a human, validating a cron string, or generating a cadence summary.

## Output

Returns a plain-English description of the schedule (e.g. 'Every weekday at 9:00 AM'), a frequency bucket (e.g. 'daily', 'hourly', 'weekly'), a boolean validation result with any error messages, and a numeric runs-per-day estimate.

## Example request

```json
{
 "input": {
  "body": {
   "timezone": "UTC",
   "expression": "0 9 * * 1-5"
  },
  "type": "http",
  "method": "POST",
  "bodyType": "json"
 }
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "required": [
      "expression"
     ],
     "properties": {
      "timezone": {
       "type": "string",
       "description": "IANA timezone name for the explanation, e.g. 'America/New_York'. Optional, default UTC."
      },
      "expression": {
       "type": "string",
       "description": "Cron expression (5, 6, or 7 fields) or macro like @daily. Max 500 chars."
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "frequency": {
       "type": "string"
      },
      "explanation": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "frequency": "daily",
  "explanation": "At 9:00 AM on every weekday"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-agentutility-ai-8b91e80d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.agentutility.ai](https://www.zero.xyz/host/x402.agentutility.ai/llms.txt)