EVM contract calls and contract creation: build, verify, sign, broadcast

Works on any EVM chain: the chain is the --chain-id N you pin (tx-build writes it into the transaction, tx-verify and tx-sign refuse any other). BlockTools has no compiler and no deploy/project management: you bring the calldata's function signature, or the init code bytes.

Contract call

1. Calldata from a signature and arguments with abi-encode, then an unsigned tx with tx-build --data (--gas is required and is never guessed: take it from your node's eth_estimateGas, see "Gas" below; --send WEI adds value for payable functions). 2. Re-verify it: tx-verify --call SIGNATURE decodes the calldata strictly (it must re-encode byte for byte) and prints the function and arguments; only an exact match lifts the generic unknown_contract_call refusal, and the destination must still be your --expect-to (the contract):

   tx-build --chain eth --chain-id 8453 --nonce 3 --max-fee-per-gas 2000000000 --gas 132358 --to 0x2B5AD5c4795c026514f8317c7a215E218DcCD6cF --data $(abi-encode 'setValue(uint256)' 42 | jq -r .data) | tx-verify --chain-id 8453 --expect-to 0x2B5AD5c4795c026514f8317c7a215E218DcCD6cF --call 'setValue(uint256)'

Without a matching --call (or --abi FILE), the selector is flagged and the tx is refused:

tx-build --chain eth --chain-id 1 --nonce 3 --max-fee-per-gas 2000000000 --gas 60000 --to 0x2B5AD5c4795c026514f8317c7a215E218DcCD6cF --data $(abi-encode 'setValue(uint256)' 42 | jq -r .data) | tx-verify --chain-id 1 --expect-to 0x2B5AD5c4795c026514f8317c7a215E218DcCD6cF

3. Sign with the same assertions; the terminal summary shows Contract call: setValue(uint256) and each argument before you type the code:

   tx-sign --tx unsigned.json --chain-id 8453 --expect-to 0x2B5AD5c4795c026514f8317c7a215E218DcCD6cF --call 'setValue(uint256)' < key

4. Broadcast: tx-broadcast --chain eth --url URL < signed.json (it shows the tx and asks for its own code).

Contract creation

tx-build --create INITCODE_HEX (or @FILE) builds a tx with no to and prints initcode_keccak256. tx-verify and tx-sign approve a creation only with --create-hash equal to keccak256 of the exact init code (no --expect-to: there is no destination yet):

tx-build --chain eth --chain-id 1 --nonce 0 --max-fee-per-gas 2000000000 --gas 226175 --create 600a600c600039600a6000f3602a60005260206000f3 | tx-verify --chain-id 1 --create-hash $(sig-hash --keccak 600a600c600039600a6000f3602a60005260206000f3 | jq -r .keccak256)

The tx-sign summary then shows the init code size and hash and New contract address: (CREATE from the signer and nonce; cross-check with create-address --deployer ADDR --nonce N).

Gas

Every --gas above is a number a node returned from eth_estimateGas, never a constant to copy: re-run the estimate on your chain, from your sender, before building. The gas schedule differs between chains and forks. The same 23-byte init code costs 56,132 on Ethereum mainnet but 226,175 on Sepolia (measured 2026-10-27 on publicnode; Sepolia runs the Amsterdam schedule, which reprices contract and account creation). An earlier version of this recipe used --gas 100000. On Sepolia that ran out of gas: tx 0xfff41592bc416223d668d3e878e9999e518e59bd5bf97054312c9f832c2cd59a got status 0x0 with gasUsed equal to the 100000 limit. The init code itself was correct; eth_call of it returns the 10-byte runtime 0x602a60005260206000f3.

rpc URL eth_estimateGas '[{"from":"0xYOUR_SENDER","data":"0x600a600c600039600a6000f3602a60005260206000f3"}]'
rpc URL eth_estimateGas '[{"from":"0xYOUR_SENDER","to":"0xCONTRACT","data":"0x<abi-encode calldata>"}]'

Read .result (hex) as --gas. The setValue example's 132358 is geth --dev's estimate for a fresh storage write to the handwritten store contract in scripts/e2e.d/evm-devnet.sh (untested); your contract will differ.

Tests

scripts/e2e.d/contract-tx.sh covers the build, verify, sign (pty) and broadcast path against a local mock that accepts bytes but does not execute the EVM. scripts/e2e.d/evm-devnet.sh (untested) runs the same path against a real geth --dev node (version and sha256 pinned in scripts/evm-pins/geth), under both the default dev schedule and Amsterdam. With gas from eth_estimateGas it checks that each creation gets receipt status 0x1, that eth_getCode equals the runtime, and that contract-call reads 42. A setValue(7) call on a store contract gets status 0x1 and reads back 7, and a plain value transfer gets status 0x1. Gas below the estimate gets status 0x0, and on Amsterdam --gas 100000 reproduces the Sepolia failure.