Agent Margin Router – Gas Fees: Live EIP-1559 gas fees (slow/standard/fast tiers) plus USD cost per transaction type (transfer, ERC-20 transfer, swap, NFT mint) for Base, Ethereum, Arbitrum, Optimism and Polygon. Aggregated from public RPC nodes – no API key. Pay per call with USDC or USDT on Base via x402. 3 free calls per wallet.