# Delx EVM Transaction Envelope Check

> Delx EVM Transaction Envelope 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 an EVM transaction envelope by checking that all required fields are present for a given transaction type and returns missing or required field lists.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/evm-tx-envelope-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/delx-evm-transaction-envelope-check-8ad67830
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zkjht9SrQz3WJZCwpLzc7

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-evm-transaction-envelope-check-8ad67830 -d '<json body>'
```

Example prompt: Can you check if my EVM transaction envelope is valid? It's a type 2 transaction with these fields: chainId, maxFeePerGas, maxPriorityFeePerGas, and nonce — tell me if anything's missing before I sign and broadcast it.

## When to prefer this

Choose this endpoint when you need a fast, stateless, in-memory preflight check that your EVM transaction envelope contains all required fields before signing or broadcasting — especially useful in agent workflows to prevent wasted gas or failed submissions. Prefer it over manual field checks when building automated transaction pipelines that must validate type 2 (EIP-1559) or other typed transactions programmatically.

## Known failure modes

- Missing or malformed 'fields' object results in validation error
- Invalid or unsupported 'transaction_type' integer may return unknown type error
- Supplying more than 128 properties in fields object violates maxProperties constraint
- Malformed JSON body returns 400-level parse error
- Network or service unavailability returns 5xx error

## How this service works

EVM Tx Envelope Check: EVM Tx Envelope Check checks required envelope fields for a declared transaction type from bounded caller-supplied values without an external provider. Call EVM Tx Envelope Check before signing, submitting, replacing, or accepting an EVM/Base transaction assembled from caller-owned data. Returns normalized transaction evidence, calculated budget or shape findings, and a fail-closed preflight status for EVM Tx Envelope Check as versioned deterministic JSON. Price: $0.001 U…

## Output

Returns a JSON object with a 'valid' boolean, a list of 'missing_fields', the full list of 'required_fields' for the given transaction type, the detected 'transaction_type', a status string ('pass' or 'fail'), and evidence metadata including whether input was retained and how many external calls were made.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "fields": {
   "type": "object",
   "description": "Fields supplied to EVM Tx Envelope Check; used only for this bounded calculation and processed in memory without retention.",
   "maxProperties": 128,
   "additionalProperties": true
  },
  "transaction_type": {
   "type": "integer",
   "description": "Transaction Type supplied to EVM Tx Envelope Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "valid": true,
   "missing_fields": [],
   "required_fields": [
    "chainId",
    "maxFeePerGas",
    "maxPriorityFeePerGas",
    "nonce"
   ],
   "transaction_type": 2
  },
  "schema": "delx/util-evm-tx-envelope-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "847b54b0f549ee1ab246ef64c6b6670897f880fa285f91e0f08548bfdd9814d7",
   "external_calls": 0
  },
  "operation": "evm_preflight:evm_tx_envelope_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-evm-transaction-envelope-check-8ad67830/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)