Transaction forensics

Explain what an EVM transaction actually did: confirmation status, the raw transaction from the chain, decoded calldata with typed parameters, the resolved function signature, and labeled counterparties.

When to use this pack

An agent (or its owner) is staring at a transaction hash and needs the plain-English story - did it confirm, which function was called, with what arguments, and is the counterparty a known contract or an unknown address.

Tools in this pack

All 5 run inside the single $0.10 call above. Each is also callable on its own if you only need one part.

• Transaction status GET /api/tx-status Check the confirmation status of a transaction by hash on Base/Polygon/Arbitrum/Optimism/Ethereum/Monad/Celo/Avalanche/Sei/Robinhood Chain: success / failed / pending / not found, with block, from, to, gas used. Read-only. ?hash=0x…&network=base
• Multi-chain EVM RPC (read-only) POST /api/evm-rpc Read-only JSON-RPC against Ethereum, Base, Polygon, Arbitrum, or Optimism with built-in multi-endpoint failover - one paid call, no node or API key of your own. Prefer the named reads (block-number, chain-info, block-info, event-logs, erc721-owner, contract-code) for common tasks - they validate inputs and cost less; use this when you need a whitelisted method they do not wrap. Whitelisted methods only: eth_blockNumber, eth_gasPrice, eth_getBalance, eth_getTransactionCount, eth_getBlockByNumber, eth_getTransactionByHash, eth_getTransactionReceipt, eth_call, eth_getCode, eth_getStorageAt, eth_chainId, eth_feeHistory, net_version. Mutating, signing, subscription, and unbounded methods (eth_getLogs) are rejected. Results over 200KB serialized return 413 - narrow the query.
• Calldata decoder (ABI or selector DB) POST /api/calldata-decode Decode EVM smart-contract transaction calldata into the function name and typed parameters. Supply an ABI (from /api/contract-abi) or a signature like transfer(address,uint256) for a fully offline decode; with neither, the 4-byte selector is resolved via the openchain.xyz signature database (4byte.directory fallback) and each candidate signature is tried. Unknown selectors return a documented partial decode (selector + raw 32-byte words) instead of an error.
• Function selector / event topic lookup POST /api/selector-lookup Resolve a 4-byte function selector or a 32-byte event topic hash to its known human-readable Solidity signatures, via the openchain.xyz signature database with 4byte.directory as fallback. Unknown selectors return {found:false} with an empty list, not an error.
• Known-address label lookup POST /api/address-label Label a known EVM address from a curated, committed dataset: major stablecoin + token contracts (USDC on every chain we settle on, USDT, DAI, WETH, WBTC), DEX routers (Uniswap, 1inch, 0x), canonical L1↔L2 bridges, large exchange hot/cold wallets, and burn/system addresses. Deterministic and offline - the provenance field states the dataset revision. Unknown addresses return {found:false}, not an error.

Workflow

1. Get the confirmation verdict from tx-status - success, revert, or still pending, plus gas used and block number.
2. Pull the raw transaction with evm-rpc eth_getTransactionByHash for the from/to addresses, value, and the input calldata.
3. Decode the calldata with calldata-decode - function name and typed parameters via ABI signature databases.
4. Cross-check the 4-byte selector with selector-lookup to surface every known signature that matches.
5. Label the counterparty with address-label - known token contract, DEX router, bridge, exchange wallet, or unknown.

Call it directly

Any x402 client pays the 402 and gets the whole workflow back in one response:

npx agent402-client call tx-forensics {"hash":"0x0000000000000000000000000000000000000000000000000000000000000000","network":"base"}

Run it in Claude

claude mcp add agent402 -s user -- npx -y agent402-mcp@latest

Then paste this prompt into Claude:

Explain what transaction 0x0000000000000000000000000000000000000000000000000000000000000000 on base actually did, using Agent402's tx-forensics skill pack. (1) Check its confirmation status, (2) fetch the raw transaction via eth_getTransactionByHash, (3) decode the calldata into the function and arguments, (4) resolve the selector against the signature databases, (5) label the destination address. Summarize as a plain-English story: what was called, with what arguments, by whom, to whom, and whether it succeeded.

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