
evm-swiss-knife
Interact with EVM-compatible blockchains using Foundry's cast tool for querying balances, calling contracts, sending transactions, and blockchain exploration. Use when needing to interact with Ethereum Virtual Machine networks via command-line, including reading contract state, sending funds, executing contract functions, or inspecting blockchain data.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/kukapay/crypto-skills --skill evm-swiss-knife- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads evm-swiss-knife automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
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 (
castcommand available) - RPC endpoint configured (via
--rpc-urlor 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> "<function_signature>" [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> "<function_signature>" [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
FAQ
What does the evm-swiss-knife skill do?
Interact with EVM-compatible blockchains using Foundry's cast tool for querying balances, calling contracts, sending transactions, and blockchain exploration. Use when needing to interact with Ethereum Virtual Machine networks via command-line, including reading contract state, sending funds, executing contract functions, or inspecting blockchain data.
How do I install evm-swiss-knife?
Run npx skills add https://github.com/kukapay/crypto-skills --skill evm-swiss-knife in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/evm-swiss-knife/ (personal) or .claude/skills/evm-swiss-knife/ (project).
Which AI agents can use evm-swiss-knife?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is evm-swiss-knife safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains evm-swiss-knife?
It is published by kukapay in kukapay/crypto-skills. It has 183 recorded installs.
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