Swap tokens and read pool state on Uniswap V4 (Base, Ethereum). Use when the agent needs to swap ERC20 tokens or ETH via Uniswap V4, get pool info (price, tick, liquidity, fees), find available pools for a token pair, set up Permit2 approvals for the Universal Router, or execute exact-input swaps. Supports Base and Ethereum mainnet. Requires `cast` (Foundry CLI) and Python 3. Write operations need a private key.