{"uid":"cap_MhPmnu4WPU12PlCs3CIlx","slug":"delx-evm-calldata-selector-extract-c6d7e322","name":"Delx EVM Calldata Selector Extract","description":"EVM Calldata Selector Extract: EVM Calldata Selector Extract extracts the first four calldata bytes as a selector from bounded caller-supplied values without an external provider. Call EVM Calldata Selector Extract 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 Selector Extract as versioned deterministic…","url":"https://api.delx.ai/api/v1/x402/evm-calldata-selector-extract","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"calldata":{"type":"string","maxLength":8192,"description":"Calldata supplied to EVM Calldata Selector Extract; used only for this bounded calculation and processed in memory without retention."}}},"responseSchema":{"type":"json","example":{"result":{"calldata":"0xa9059cbb0000000000000000000000001111111111111111111111111111111111111111","selector":"0xa9059cbb","byte_count":36,"shape_valid":true},"schema":"delx/util-evm-calldata-selector-extract/v1","status":"pass","evidence":{"retained":false,"input_sha256":"1048e8d74a53c6ea3249086735deac2cb24ee3dd131a3852df0439253301d8de","external_calls":0},"operation":"evm_preflight:evm_calldata_selector_extract"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_qXOGOzXF-tXCIXGBBLSBH","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Extracts the 4-byte function selector from raw EVM transaction calldata and validates its shape.","exampleAgentPrompt":"Extract the function selector from this EVM calldata hex string: 0xa9059cbb0000000000000000000000001111111111111111111111111111111111111111 — tell me the 4-byte selector, total byte count, and whether the shape is valid.","exampleUseCases":[{"title":"Pre-flight check before contract call","prompt":"Before I submit this transaction, parse the calldata 0xa9059cbb000000000000000000000000abcdef1234567890abcdef1234567890abcdef12000000000000000000000000000000000000000000000000016345785d8a0000 and tell me the function selector and whether the format looks valid."},{"title":"Identify function being invoked","prompt":"I have this raw hex calldata from a pending Ethereum transaction: 0x23b872dd000000000000000000000000abc... — what function selector does it start with and how many bytes is the calldata total?"},{"title":"Validate calldata shape for agent pipeline","prompt":"Check if this EVM calldata 0x095ea7b30000000000000000000000001234567890abcdef1234567890abcdef12345678ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff is well-formed and extract its 4-byte selector so I can route it correctly."}],"resultDescription":"Returns the original calldata, the extracted 4-byte function selector (e.g. 0xa9059cbb), total byte count, a boolean shape_valid flag indicating whether the calldata is properly formed, plus evidence fields including whether input was retained (always false), the SHA-256 hash of the input, and external call count (always 0).","failureModes":["Invalid or non-hex calldata string returns a failed parse result","Calldata shorter than 4 bytes may result in shape_valid: false","Input exceeding 8192 character limit may be rejected","Malformed JSON request body returns HTTP 400"],"whenToPreferThis":"Use this endpoint when an AI agent needs to inspect or validate raw EVM calldata before executing or routing a smart contract transaction, especially during preflight checks in automated blockchain workflows. Prefer this over manual parsing when you need a verifiable, auditable result with SHA-256 evidence and no data retention guarantees.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T01:17:00.460Z","isFirstParty":false}