EVM Swiss Knife This skill enables interaction with EVM-compatible blockchains through Foundry's cast command-line tool. It covers common blockchain operations like balance queries, contract calls, transaction sending, and network inspection. Installation To use this skill, you need Foundry installed, which provides the cast command. Follow the official installation guide: https://getfoundry.sh/introduction/installation Quick Install (Linux/Mac) Install Foundryup: curl -L https://foundry.paradigm.xyz | bash Source your shell configuration or start a new terminal: source ~/.bashrc

or ~/.zshrc

Install Foundry: foundryup Verify installation: cast --version For other platforms or detailed instructions, see the full guide at https://getfoundry.sh/introduction/installation Prerequisites Foundry installed ( cast command available) RPC endpoint configured (via --rpc-url or environment variables) Private key for transaction operations (if sending txs) RPC URL Selection To interact with different EVM networks, you need reliable RPC endpoints. Use ChainList's API at https://chainlist.org/rpcs.json to get a comprehensive JSON list of RPC URLs for all supported chains. How to Select RPC URLs: Fetch the RPC data: curl -s https://chainlist.org/rpcs.json | jq '.[] | select(.chainId == 1)'

For Ethereum (chain ID 1)

Look for RPC URLs that are:

Public and free

No API keys required

No or limited tracking

Avoid URLs with "tracking": "yes"

Fast and reliable

Prefer URLs with low latency or high score

Open source

Prefer community-maintained endpoints Popular choices (extracted from ChainList): Ethereum (ID 1): https://ethereum-rpc.publicnode.com BNB Smart Chain (ID 56): https://bsc-dataseed.binance.org Base (ID 8453): https://mainnet.base.org Polygon (ID 137): https://polygon-rpc.com For production use, consider paid RPC services like Alchemy, Infura, or QuickNode for higher reliability and rate limits. Always verify the chain ID matches your intended network to avoid connecting to wrong chains. Common Operations Query Account Balance Get ETH balance of an address: cast balance < address

--rpc-url < rpc_url

Get ERC20 token balance: cast call < token_contract

"balanceOf(address)(uint256)" < address

--rpc-url < rpc_url

Call Contract Functions (Read-Only) Call a view/pure function: cast call < contract_address

"" [ args .. . ] --rpc-url < rpc_url

Example - get token total supply: cast call 0xA0b86a33E6441e88C5F2712C3E9b74B6F3f5a8b8 "totalSupply()(uint256)" --rpc-url < rpc_url

Send Transactions Send ETH: cast send --private-key < pk

--rpc-url < rpc_url

< to_address

--value < amount_in_wei

Call contract function (write): cast send --private-key < pk

--rpc-url < rpc_url

< contract_address

"" [ args .. . ] Blockchain Inspection Get latest block number: cast block-number --rpc-url < rpc_url

Get block details: cast block < block_number

--rpc-url < rpc_url

Get transaction details: cast tx < tx_hash

--rpc-url < rpc_url

Contract Deployment Deploy a contract: cast send --private-key < pk

--rpc-url < rpc_url

--create < bytecode

[ constructor_args .. . ] Decoding Data Decode hex data: cast --to-ascii < hex_string

cast --to-dec < hex_string

Network-Specific Examples Ethereum Mainnet export ETH_RPC_URL = https://eth-mainnet.alchemyapi.io/v2/YOUR_API_KEY cast balance 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 Polygon cast balance < address

--rpc-url https://polygon-rpc.com/ Local Development (Anvil) cast balance < address

--rpc-url http://127.0.0.1:8545 Error Handling RPC errors: Check endpoint URL and network connectivity Insufficient funds: Ensure account has enough ETH for gas + value Contract errors: Verify function signatures and parameter types Private key errors: Ensure correct format (0x prefixed hex) Advanced Usage Batch Operations Use shell loops for multiple queries: for addr in addr1 addr2 addr3 ; do echo "Balance of $addr : $( cast balance $addr --rpc-url $RPC_URL ) " done Gas Estimation Estimate gas for a transaction: cast estimate --rpc-url < rpc_url

< to_address

--value < amount

ABI Interactions For complex contracts, save ABI to file and use: cast call --abi < abi_file

< contract

< function

[ args .. . ] Security Notes Never expose private keys in scripts or logs Use environment variables for sensitive data Test on testnets before mainnet operations Verify contract addresses and function signatures Monitor gas prices for transaction timing