{"uid":"cap_Uz90o32XWjzU1VZkS7UC9","slug":"signalharness-evm-storage-slot-compute-695a1c5f","name":"SignalHarness EVM Storage Slot Compute","description":"Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.","url":"https://signalharness.ai/api/agent/services/evm_storage_slot_compute/invoke","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"storage_slot_request":{"type":"string","maxLength":65536,"minLength":2}}},"responseSchema":{"type":"json","example":{"replay":false,"result":{"warnings":["The caller must supply the correct layout and key encoding."],"service_id":"evm_storage_slot_compute","evidence_scope":"caller_supplied_data","computed_storage_slot":"{\"key_type\":\"address\",\"kind\":\"mapping\",\"slot\":\"0xada5013122d395ba3c54772283fb069b10426056ef8ca54750cb9bb552a59e7d\"}"},"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":"evm_storage_slot_compute","executionId":"example-execution","startedAtMs":0,"amountAtomic":"10000","resultSha256":"94541795270ec7665897e175fb93dc62b62434198e94b61c30e6dd324d327b5c","serviceVersion":"1.0.0","settlementReference":"0x0000000000000000000000000000000000000000000000000000000000000000"},"artifacts":[],"requestId":"example-request","executionId":"example-execution"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","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":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_B6qbF1bCX8fq66wPPD4E6","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the EVM storage slot for a given smart contract storage variable based on caller-supplied input data.","exampleAgentPrompt":"Can you compute the EVM storage slot for the 'balances' mapping in a Solidity contract where the key is address 0xABC123... and balances is at slot 0? I need the exact storage slot value.","exampleUseCases":[{"title":"Read raw balance from contract storage","prompt":"I need to call eth_getStorageAt on an ERC-20 contract to read a specific user's balance directly — can you compute the storage slot for the 'balances' mapping at base slot 1 with key address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045?"},{"title":"Verify upgradeable proxy implementation slot","prompt":"What is the EVM storage slot for the implementation address in an OpenZeppelin TransparentUpgradeableProxy? I want to double-check the slot before calling eth_getStorageAt on mainnet."},{"title":"Debug Solidity storage layout collision","prompt":"I think two variables in my Solidity contract are colliding in storage — can you compute the slots for a uint256 at position 2 and the first element of a dynamic array also declared around slot 2 so I can compare them?"}],"resultDescription":"Returns a JSON object containing the computed EVM storage slot as a hex string, any relevant warnings about the input (e.g. ambiguous layout), the service ID, and an evidence scope field indicating the data was caller-supplied. Also includes a full receipt with payment ID, network (Base/eip155:8453), latency, and a SHA-256 hash of the result for auditability.","failureModes":["Malformed or ambiguous storage_slot_request string returns an error or warning-laden result","Unsupported storage layout patterns may produce incorrect slots without error","Input exceeding 65536 characters is rejected","Missing required fields in the request body returns a 400-level error","Payment failure via x402 protocol results in 402 response before execution"],"whenToPreferThis":"Choose this endpoint when you need programmatic, on-demand EVM storage slot derivation without setting up a local Solidity compiler or ABI decoder. It is particularly useful for agents that need to call eth_getStorageAt dynamically, audit contract storage layouts, or verify proxy implementation slots — especially when the agent cannot run code locally. At $0.01 USDC per call via x402, it is cost-effective for one-off lookups within an agentic workflow on Base.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-16T13:06:38.684Z","isFirstParty":false}