Prices a swap between sell and buy across the indexed venues and stores it under a quoteId.

• Cost: 0.01 USDC per call over x402: the first call gets a 402 with payment requirements in the PAYMENT-REQUIRED header (base64 JSON); sign them and retry with a PAYMENT-SIGNATURE header carrying the payment payload.

• sell / buy: two different assets (native and ERC-20 USDC count as the same asset; either side may be USDC). Resolve a ticker with POST /trade/v1/search first.

• Response shape: when one side is USDC, best.type is direct/two_hop/split and best.legs lists one leg per path actually used; routes[] lists every discovery candidate. When neither side is USDC, or when a USDC-side allocation can't be expressed as legs, best.type is graph, best.legs is empty, and the execution plan is in best.graph. Both shapes support side: exactIn and exactOut, and both execute the same way through POST /trade/v1/swap.

• amount: a human-readable decimal string in the token's own units, e.g. "1.5" for 1.5 USDC, not base units. It is the sell amount for side: exactIn and the buy amount for side: exactOut.

• Optional: side (exactIn/exactOut), slippageBps, split and hop limits, venues/excludeVenues (ids from GET /trade/v1/venues), taker, ttlSec.

• Executability: POST /trade/v1/swap executes every quote through ArcgateRouter. best.executable is false, with warning graph_execution_unavailable, when no ArcgateRouter is configured (or, for an Aerodrome edge, no Aerodrome router), or when the operator has disabled a selected path's venue - even with both routers configured. In that last case, POST /trade/v1/swap may still fall back to an executable candidate the quote already priced instead of failing outright.

• Readiness: name the wallet that will trade in taker and the answer carries readiness, read at the quote's block: whether that wallet holds the input (balance), which approval or Permit2 signature POST /trade/v1/swap will need (approval for the default permit2, approve for approval: "approve"), enough native USDC for gas (gas), and whether this call's x402 payer can pay the swap fee (fees). totalCostUsdc is the swap fee plus gas: what finishing costs. When ready is false, next is stop. Without taker there is no readiness.

• Lifetime: the quoteId is good for ttlSec seconds (default and max 120).

• Next: POST /trade/v1/swap with the returned quoteId. Costs 10000 base units (0.01 USDC) per call. Payment goes in params._meta["x402/payment"]; use an x402-aware MCP client (see https://docs.arcgate.dev/#arcgate/description/mcp-for-agents).