# Delx EVM Legacy Fee Check

> Delx EVM Legacy Fee 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 whether a legacy (Type 0) EVM transaction's computed gas fee falls within a specified maximum budget ceiling.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/evm-legacy-fee-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-legacy-fee-check-bb971774
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fUvKmWJAI-S_w8OgjaW5r

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-legacy-fee-check-bb971774 -d '<json body>'
```

Example prompt: Before I broadcast this legacy Ethereum transaction, check whether the fee is within budget — gas limit is 21000, gas price is 10000000000 wei, and my maximum fee ceiling is 300000000000000 wei.

## When to prefer this

Use this endpoint when you need a fast, stateless, in-memory preflight check for legacy (Type 0) EVM transactions before broadcasting — particularly in agent pipelines where you want to gate transaction submission on a fee ceiling without making any external blockchain calls. Prefer this over on-chain simulation when you only need arithmetic validation of gas_limit × gas_price_wei against a budget, and you want a verifiable evidence trail (input hash, zero retention, zero external calls).

## Known failure modes

- Missing required fields (gas_limit, gas_price_wei, or maximum_fee_wei) returns a validation error
- Non-numeric or malformed wei strings cause parse errors
- Gas price or maximum fee strings exceeding 8192 characters are rejected
- Integer overflow for extremely large gas values may produce unexpected results

## How this service works

EVM Legacy Fee Check: EVM Legacy Fee Check checks gasPrice and gasLimit values for a legacy transaction budget from bounded caller-supplied values without an external provider. Call EVM Legacy Fee 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 Legacy Fee Check as versioned deterministic JSON. Price: $0.001 U…

## Output

Returns a JSON object indicating whether the computed fee (gas_limit × gas_price_wei) is within the specified maximum_fee_wei ceiling. Includes a boolean `within_budget` field, the computed `fee_ceiling_wei` value, a pass/fail `status`, and an evidence block confirming no data was retained and no external calls were made.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "gas_limit": {
   "type": "integer",
   "description": "Gas Limit supplied to EVM Legacy Fee Check; used only for this bounded calculation and processed in memory without retention."
  },
  "gas_price_wei": {
   "type": "string",
   "maxLength": 8192,
   "description": "Gas Price Wei supplied to EVM Legacy Fee Check; used only for this bounded calculation and processed in memory without retention."
  },
  "maximum_fee_wei": {
   "type": "string",
   "maxLength": 8192,
   "description": "Maximum Fee Wei supplied to EVM Legacy Fee Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "within_budget": true,
   "fee_ceiling_wei": "21000000000000"
  },
  "schema": "delx/util-evm-legacy-fee-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "3f479705a06db86ca332b2883b0bc646d76b8b39f7fea2aa864a00ee6e549ded",
   "external_calls": 0
  },
  "operation": "evm_preflight:evm_legacy_fee_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-evm-legacy-fee-check-bb971774/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)