You pre-fund a wallet, mint one key, and point the MCP client you already use at the gateway. We authenticate the call, check it against your balance and that key’s 24-hour cap, charge a fixed price, route it to the tool, and stream the answer back.
New here? Start with the quickstart — four steps to a paid call.
Everything in these docs#
Start here
- OverviewWhat the gateway does for you, and what it costs.
- QuickstartFund a wallet, mint a key, make a paid call. Copy-paste.
- Using an MCP clientPoint the client you already use at the gateway. No SDK.
Keys and limits
- Keys, caps and rotationTen keys, an optional rolling 24-hour cap, immediate revocation.
- Rate limitsWhat is metered, what a 429 means, and how to back off.
Money
- When you are chargedThe one case you pay for a failure, and why.
- IdempotencyA safe retry, and the 422 that refuses an unsafe one.
- Money is a stringInteger micro-USD, and the 2^53 bug it prevents.
- Funding and spendTop-ups, the card fee, and seeing where it went.
Reference
- Every error codeGenerated from the gateway's source, so it cannot fall behind.
- HeadersWhat you send, what you get back, what is never forwarded.
What you can rely on#
- A price you can see before you call. Fixed per tool version, and a published version’s price can never change.
- A ceiling you set. Your wallet balance bounds everything, there is no auto-top-up, and no heuristic of ours lowers a cap you chose.
- No charge for our failures. A 402, 429 or 503 is never billed, and a tool that fails before delivering anything is refunded automatically.
- Your key never reaches a creator. It is consumed at the gateway and stripped.
- Your payloads are not stored. Nexus402 does not store or log the contents of tool calls. The gateway reads only the request envelope (method and tool name) to route and bill, and computes a one-way hash. See the Privacy Policy.