Fetch perpetual-futures funding-rate intelligence for a given base asset (e.g. 'BTC', 'ETH', 'SOL') aggregated across 17 major perp venues — Binance, Bybit, OKX, BitMEX, Deribit, dYdX, Hyperliquid, Bitfinex, Huobi, Kraken, Phemex, WOO X, Aster, Lighter, Coinbase, Gate.io, Vertex. Returns per-exchange rate + USD open interest, OI-weighted aggregate funding, divergence in bps, and max/min funding exchange — pre-computed for perp-arbitrage bots. Priced at $0.01 USDC on Base (x402). Pass a signed x402 v2 authorization as the '_payment' argument to unlock the paid response. Without it, the tool returns the 402 accept-list for your wallet to sign.