# Base Fee Cap Analyzer

> Base Fee Cap Analyzer is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).

Analyzes EVM transaction fee parameters (base fee, max fee cap, priority fee) for Base network transactions and returns gas cost breakdown with cap headroom and inclusion context.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/base_fee_cap_analyze/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-fee-cap-analyzer-b488aaa9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yhzLTFKHnKiEQs4ipTaBS

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 base-fee-cap-analyzer-b488aaa9 -d '<json body>'
```

Example prompt: Analyze my Base transaction fee parameters: base_fee_per_gas is 100 wei, max_fee_per_gas is 120 wei, max_priority_fee_per_gas is 0, and gas is 21000 — tell me the cap headroom, effective gas price, and total execution fee.

## When to prefer this

Use this endpoint when you need to programmatically validate or decompose EVM transaction fee parameters specifically on Base (OP Stack L2) before or after submission. It is purpose-built for Base/OP Stack fee model analysis (L2 execution + L1 data components) rather than generic Ethereum mainnet gas estimators. Prefer this when you want structured cap headroom analysis, not just a raw gas price estimate.

## Known failure modes

- Invalid or malformed request_json yields a parsing error
- Missing required fee fields in the JSON input causes incomplete analysis
- Unsupported chain ID returns network context mismatch or error
- max_fee_per_gas lower than base_fee_per_gas may trigger a warning about non-inclusion
- Empty or too-short request_json rejected by schema minLength:2 constraint

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns a structured JSON analysis including: cap_headroom (difference between max fee and base fee), effective_gas_price, execution_fee (total in wei), realized_priority_fee_per_gas, fee mode classification, and network context describing the OP Stack chain configuration (accepted chain IDs, deposit transaction type, fee model). Also returns warnings if live inclusion probability cannot be estimated.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "request_json": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 2
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "No live inclusion probability is estimated."
   ],
   "service_id": "base_fee_cap_analyze",
   "analysis_json": "{\"base_fee_per_gas\":\"100\",\"cap_headroom\":\"20\",\"effective_gas_price\":\"100\",\"execution_fee\":\"2100000\",\"gas\":\"21000\",\"max_fee_per_gas\":\"120\",\"max_priority_fee_per_gas\":\"0\",\"mode\":\"evm_fee\",\"network_context\":{\"accepted_chain_ids\":[\"8453\",\"84532\"],\"deposit_transaction_type\":\"0x7e\",\"fee_model\":\"L2 execution plus caller-supplied L1 data/operator components\",\"protocol_family\":\"OP Stack\"},\"realized_priority_fee_per_gas\":\"0\"}",
   "evidence_scope": "caller_supplied_data",
   "analyzed_network": "base"
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "base_fee_cap_analyze",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "de63bbd4b0d60ac237e51de0bb447f3afa0a2b9a3c8fe7e354209cb4a72b6aeb",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-fee-cap-analyzer-b488aaa9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)