{"uid":"cap_szEkrOC_tGnkjLItdNfrC","slug":"base-toolbox-uniswap-v3-preflight-check-b8bca918","name":"Base Toolbox Uniswap v3 Preflight Check","description":"Base toolbox: before you sign on Base — Uniswap v3 preflight, leftover allowances, tx explain, transfer check. $0.10 USDC. Also $0.001 price/gas/ENS. GET /v1/constants free. No CoinGecko key.","url":"https://basetoolbox.cartonpliant.workers.dev/v1/preflight","method":"POST","headers":{},"bodySchema":{"properties":{"input":{"type":"object"},"output":{"type":"object"}}},"responseSchema":{"type":"json","example":{"ok":true,"next":"swap","minOut":"…","sellable":true,"warnings":[],"amountOut":"…"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.1","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.1/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.1","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.1","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_NB7e0zBVDNQQ6SMA8dHMT","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.1","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Validates a Uniswap v3 swap on Base before signing — checks token sellability, expected output amount, and warnings about the transaction.","exampleAgentPrompt":"Before I sign this swap, run a preflight check on Base to see if I can sell my USDC for ETH on Uniswap v3 — tell me the expected output, minimum I'd receive, and any warnings I should know about.","exampleUseCases":[{"title":"Safe swap validation before signing","prompt":"I'm about to swap 500 USDC for WETH on Uniswap v3 on Base — can you run a preflight check first and tell me the expected output amount, the minimum I'd get, and whether there are any warnings I should worry about?"},{"title":"Check token sellability on Base","prompt":"Is PEPE actually sellable on Uniswap v3 on Base right now? Run a preflight before I try to swap it — I don't want to sign a transaction that's going to fail."},{"title":"Verify allowance and swap output before trade","prompt":"I want to swap 1000 DAI to USDC on Base via Uniswap v3 — check my leftover allowances and simulate the swap so I know what I'd receive before I approve anything."}],"resultDescription":"A JSON object indicating whether the swap is safe to proceed (ok), the recommended next action (next), expected output amount (amountOut), minimum acceptable output (minOut), whether the token is sellable (sellable), and an array of any warnings about the transaction.","failureModes":["Token not tradeable on Uniswap v3 Base — sellable: false","Insufficient liquidity for the requested trade size","Payment not received or invalid USDC payment — 402 response","Malformed input object missing required swap parameters","Slippage or price impact too high — warning in warnings array","Token contract address not recognized on Base network"],"whenToPreferThis":"Choose this endpoint when you need to validate a Uniswap v3 swap on Base chain before the user signs — particularly when you want to surface warnings, confirm token sellability, or calculate expected output without executing a transaction. Prefer this over on-chain simulation when you want a cheap ($0.10 USDC), fast, pre-packaged preflight that also checks allowances and explains the transaction.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T18:42:17.192Z","isFirstParty":false}