# Delx Payload Size Check

> Delx Payload Size Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).

Measures the byte size of a payload against configurable soft and hard ceiling limits, returning a deterministic pass/warn/fail result before a paid operation is attempted.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/payload-size-check
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-payload-size-check-02589300
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ADwLegxjmVX7jQQ-1HtkW

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 delx-payload-size-check-02589300 -d '<json body>'
```

Example prompt: Before I send this request, check if the payload is within size limits — soft ceiling 10000 bytes, hard ceiling 20000 bytes — and tell me whether it passes, warns, or fails.

## When to prefer this

Choose this endpoint when you need a stateless, deterministic, sub-cent preflight check on payload byte size before committing to a downstream operation — especially before making paid API calls, sending large messages, or dispatching agent context. Prefer it over client-side size estimates when you want a guaranteed machine-readable pass/warn/fail verdict that can be logged or acted upon programmatically.

## Known failure modes

- Missing payload field returns validation error
- Non-integer limit values cause schema rejection
- Extremely nested objects may produce unexpected byte counts depending on serialization
- Soft limit greater than hard limit may return ambiguous results
- Empty payload may return zero-byte result without error

## How this service works

Measure payload byte size against soft and hard ceilings before paying — first-party local utility for agent preflight and proven micro-utils expansion. Returns deterministic machine-readable JSON for $0.001 USDC via x402 on Base. Execution is first-party, local-only, stateless, and memory-only with no paid upstream, no input retention, no web search, no live RPC, and no mediagen. Results are advisory; the caller owns authorization, budgets, and production controls. Sibling of Delx routes that…

## Output

Returns deterministic machine-readable JSON indicating the exact byte size of the provided payload, whether it breaches the soft limit (advisory warning), and whether it breaches the hard limit (hard failure signal). All results are advisory; no state is stored and no upstream calls are made.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "payload": {
   "type": "object",
   "description": "Input field: payload."
  },
  "hard_limit_bytes": {
   "type": "integer",
   "description": "Input field: hard limit bytes."
  },
  "soft_limit_bytes": {
   "type": "integer",
   "description": "Input field: soft limit bytes."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "bytes": 17,
  "chars": 17,
  "schema": "delx/util-payload-size-check/v1",
  "status": "ok",
  "within_hard": true,
  "within_soft": true,
  "hard_limit_bytes": 65536,
  "soft_limit_bytes": 8192,
  "recommend_truncate": false
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-payload-size-check-02589300/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)