# Friday Seller Tools – Field Limit Validator

> Friday Seller Tools – Field Limit Validator is a paid API for AI agents from friday-seller-tools-production.up.railway.app, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-15).

Validates marketplace listing fields (Amazon, Walmart, Shopify, eBay) against platform-specific character and content limits before upload.

## Facts

- Endpoint: POST https://friday-seller-tools-production.up.railway.app/v1/listings/field-limit-validate
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/friday-seller-tools-field-limit-validator-b914bfb4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fcD2xyoqK0DXY6s0U4TNd

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 friday-seller-tools-field-limit-validator-b914bfb4 -d '<json body>'
```

Example prompt: Can you check whether my Amazon listing fields are within the allowed character limits — I want to validate my product title, five bullet points, and description before I upload them?

## When to prefer this

Choose this endpoint when you need to pre-validate marketplace listing fields against platform-specific character limits before attempting an upload to Amazon, Walmart, Shopify, or eBay. It is especially useful in automated listing pipelines to catch field-length violations early, avoiding rejected uploads and wasted listing fees.

## Known failure modes

- Invalid or missing platform identifier returns validation error
- Malformed field input causes 400 bad request
- Unsupported marketplace platform returns unsupported error
- Empty field values may return inconclusive validation
- Service unavailable on Railway deployment returns 5xx

## How this service works

Instant, low-cost Amazon, Walmart, Shopify, and eBay listing, upload-preparation, advertising, and image-brief deliverables.

## Output

Returns a job ID and status (queued/complete) along with field-level validation results indicating which listing fields pass or fail marketplace-specific character and content limits, with details on violations.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "title": {
   "anyOf": [
    {
     "type": "string",
     "maxLength": 5000,
     "minLength": 1
    },
    {
     "type": "null"
    }
   ],
   "title": "Title",
   "default": null
  },
  "bullets": {
   "anyOf": [
    {
     "type": "array",
     "items": {
      "type": "string",
      "maxLength": 5000,
      "minLength": 1
     },
     "maxItems": 20,
     "minItems": 1
    },
    {
     "type": "null"
    }
   ],
   "title": "Bullets",
   "default": null
  },
  "overrides": {
   "type": "array",
   "items": {
    "type": "object",
    "title": "FieldLimitOverride",
    "required": [
     "field",
     "max_units",
     "unit"
    ],
    "properties": {
     "unit": {
      "enum": [
       "characters",
       "bytes"
      ],
      "type": "string",
      "title": "Unit"
     },
     "field": {
      "enum": [
       "title",
       "bullet",
       "description",
       "search_terms"
      ],
      "type": "string",
      "title": "Field"
     },
     "max_units": {
      "type": "integer",
      "title": "Max Units",
      "maximum": 1000000,
      "minimum": 1
     }
    },
    "description": "Seller-supplied cap that replaces the built-in default for one field kind.",
    "additionalProperties": false
   },
   "title": "Overrides",
   "maxItems": 8
  },
  "description": {
   "anyOf": [
    {
     "type": "string",
     "maxLength": 100000,
     "minLength": 1
    },
    {
     "type": "null"
    }
   ],
   "title": "Description",
   "default": null
  },
  "marketplace": {
   "enum": [
    "amazon_us",
    "walmart_us",
    "shopify",
    "ebay_us"
   ],
   "type": "string",
   "title": "Marketplace",
   "default": "amazon_us"
  },
  "search_terms": {
   "anyOf": [
    {
     "type": "string",
     "maxLength": 5000,
     "minLength": 1
    },
    {
     "type": "null"
    }
   ],
   "title": "Search Terms",
   "default": null
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "job_id": "example",
  "status": "queued"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/friday-seller-tools-field-limit-validator-b914bfb4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from friday-seller-tools-production.up.railway.app](https://www.zero.xyz/host/friday-seller-tools-production.up.railway.app/llms.txt)