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Delx EVM Calldata Shape Check
x402
Delx EVM Calldata Shape 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 the structural shape and byte count of EVM calldata hex strings without retaining or executing them.
Price / call$0.001
Success—
StatusUnknown
How this service works
EVM Calldata Shape Check: EVM Calldata Shape Check checks 0x-prefixed calldata for even-length hexadecimal bytes from bounded caller-supplied values without an external provider. Call EVM Calldata Shape 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 Calldata Shape Check as versioned deterministic JSON. Price…
Output
Returns a JSON object with the original calldata, its byte count, a shape_valid boolean indicating structural correctness, an operation label, a schema identifier, a status field ('pass' or 'fail'), and an evidence block including a SHA256 hash of the input, confirmation that no data was retained, and a count of zero external calls made.
Example use cases
Preflight check before gas estimation
“Before I estimate gas for this transaction, can you verify the calldata shape is valid? Here's the hex: 0xa9059cbb000000000000000000000000abcdefabcdefabcdefabcdefabcdefabcdefabcd0000000000000000000000000000000000000000000000000de0b6b3a7640000”
Debugging malformed contract call
“My ERC-20 transfer call keeps failing — can you check if this calldata is well-formed and give me the byte count so I can figure out what's wrong: 0xa9059cbb00000000000000000000000012345678”
Validating agent-generated calldata
“I just had an agent encode a contract interaction — can you run a shape check on this calldata to confirm it's structurally correct before I broadcast it: 0x23b872dd000000000000000000000000aabbccdd11223344556677889900aabbccdd112233”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/evm-calldata-shape-checkWhen to prefer
Choose this endpoint when you need a lightweight, privacy-preserving preflight check on EVM calldata shape before broadcasting a transaction or estimating gas. It is ideal for agent pipelines that generate or transform calldata and need a quick structural sanity check without executing anything on-chain or exposing calldata to stateful external services. Prefer it over full simulation tools when you only need byte-level shape validation, not execution traces or revert analysis.
Side effects
- Invalid or non-hex calldata string returns shape_valid false
- Calldata exceeding 8192 characters is rejected by schema validation
- Malformed JSON request body causes a 400-level error
- Empty calldata field may return an error or shape_valid false
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| calldata | string | Calldata supplied to EVM Calldata Shape Check; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"calldata": "0xa9059cbb0000000000000000000000001111111111111111111111111111111111111111",
"byte_count": 36,
"shape_valid": true
},
"schema": "delx/util-evm-calldata-shape-check/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "1048e8d74a53c6ea3249086735deac2cb24ee3dd131a3852df0439253301d8de",
"external_calls": 0
},
"operation": "evm_preflight:evm_calldata_shape_check"
}
}Tags
x402
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