# JSON Required Fields Check

> JSON Required Fields Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Validates a JSON object for absent or null required top-level fields, returning counts and normalized findings as versioned deterministic JSON.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/json-required-fields-check
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/json-required-fields-check-57d28020
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_a_B1kFg2P98ED2D8HOmom

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 json-required-fields-check-57d28020 -d '<json body>'
```

Example prompt: Before sending this order payload to the fulfillment API, check it against the required fields ["order_id", "customer_email", "items", "shipping_address"] and tell me which ones are missing or null.

## When to prefer this

Use this endpoint when an AI agent needs a fast, deterministic, in-memory check that a JSON object satisfies a required-field contract before handing it to a stricter downstream tool or API. Prefer it over custom code when you need a versioned, auditable result with field counts rather than a simple boolean, and when you want to avoid retaining sensitive payload data.

## Known failure modes

- Object exceeds 128 property limit — request rejected
- required_fields array exceeds 256 items — request rejected
- Malformed input (non-object passed as 'object') — validation error returned
- Individual field name string exceeds 8192 characters — item rejected
- Network or upstream availability error — HTTP 5xx

## How this service works

JSON Required Fields Check: JSON Required Fields Check finds absent or null required top-level fields from bounded caller-supplied values without an external provider. Call JSON Required Fields Check before an agent hands structured data or a batch plan to a downstream tool with a stricter contract. Returns the bounded transformation or validation finding with counts, normalized values, and a versioned result contract for JSON Required Fields Check as versioned deterministic JSON. Price: $0.001…

## Output

Returns a versioned deterministic JSON object including: a list of missing fields, a list of null fields, counts of each, normalized values where applicable, and a versioned result contract identifier. No data is retained after processing.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "object": {
   "type": "object",
   "description": "Object supplied to JSON Required Fields Check; used only for this bounded calculation and processed in memory without retention.",
   "maxProperties": 128,
   "additionalProperties": true
  },
  "required_fields": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Required Fields supplied to JSON Required Fields Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "complete": true,
   "missing_fields": []
  },
  "schema": "delx/util-json-required-fields-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "3b8f29cd44e029a44371d04cd51467653d8699dd08fc8eb6f9c55cb1aa0707d8",
   "external_calls": 0
  },
  "operation": "data_batch:json_required_fields_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/json-required-fields-check-57d28020/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)