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Base UserOperation Inspector
x402
Base UserOperation Inspector is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-15).
Analyzes and decodes a raw ERC-4337 UserOperation JSON for the Base network, returning gas breakdown, call selector, paymaster status, nonce, and network context without simulating on-chain.
Price / call$0.02
Success—
StatusUnknown
How this service works
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Output
Returns a structured analysis JSON containing: the decoded call selector, gas parameters (callGasLimit, verificationGasLimit, preVerificationGas, maxFeePerGas, maxPriorityFeePerGas), max gas units, max fee exposure in base units, boolean flags for paymaster and initCode presence, nonce, sender address, and network context including accepted chain IDs (Base mainnet 8453 and testnet 84532), deposit transaction type, and fee model description. Also includes warnings about simulation and signature verification limitations.
Example use cases
Pre-submission UserOperation gas audit
“I'm about to submit this UserOperation to the Base bundler — can you decode it and tell me the callGasLimit, verificationGasLimit, preVerificationGas, and the total max fee exposure so I know if the gas settings look reasonable?”
Identify target function from callData
“Can you inspect this UserOperation and extract the call selector from the callData so I can confirm it's actually calling the ERC-20 transfer function and not something else?”
Validate paymaster and initCode flags
“Parse this UserOperation JSON and tell me whether it includes a paymaster and whether it has an initCode — I need to know if this is a new wallet deployment and if gas is being sponsored.”
Technical details
Endpoint
POSThttps://signalharness.ai/api/agent/services/base_user_operation_inspect/invokeWhen to prefer
Choose this endpoint when you need lightweight, off-chain static analysis of an ERC-4337 UserOperation targeting the Base network — particularly to decode callData selectors, audit gas parameters, check paymaster/initCode flags, or understand fee exposure before bundler submission. It does not simulate execution or verify signatures, so it is not a substitute for full bundler simulation, but it is fast, cheap ($0.02 USDC), and requires no RPC access.
Side effects
- Malformed or non-JSON request_json input returns a parse error
- Missing required UserOperation fields may produce incomplete analysis with warnings
- Signatures and paymaster validity are NOT verified — analysis is caller-supplied data only
- Chain IDs outside Base mainnet/testnet (8453/84532) may not be recognized
- Extremely large UserOperation blobs may hit the 65536 character maxLength limit
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| request_json | string |
Output
Schema · Response
{
"type": "json",
"example": {
"replay": false,
"result": {
"warnings": [
"Does not simulate, hash against an EntryPoint, or verify signatures unless all required evidence is supplied."
],
"service_id": "base_user_operation_inspect",
"analysis_json": "{\"call_selector\":\"0xa9059cbb\",\"gas\":{\"callGasLimit\":\"21000\",\"maxFeePerGas\":\"120\",\"maxPriorityFeePerGas\":\"5\",\"preVerificationGas\":\"21000\",\"verificationGasLimit\":\"100000\"},\"has_init_code\":false,\"has_paymaster\":false,\"max_fee_exposure\":\"17040000\",\"max_gas_units\":\"142000\",\"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\"},\"nonce\":\"1\",\"sender\":\"0x0000000000000000000000000000000000000001\"}",
"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_user_operation_inspect",
"executionId": "example-execution",
"startedAtMs": 0,
"amountAtomic": "20000",
"resultSha256": "d167cfe6d2b6c4b06eb4270b3bf33d6c8e26a7a80cd412f527bd8226210149b4",
"serviceVersion": "1.0.0",
"settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
},
"artifacts": [],
"requestId": "example-request",
"executionId": "example-execution"
}
}Tags
x402
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