Documentation
Nexus402 documentation
A monetization and security clearinghouse for MCP tools. Developers pre-fund a wallet and call tools with one key; creators host an endpoint and get paid per call.
I want to call tools
Developer docs
Pre-fund a wallet, mint one key, and point the MCP client you already use at the gateway. Caps, billing, idempotency and every error code.
All 11 pages →I want to publish a tool
Creator docs
Host an ordinary HTTP endpoint and get paid per call. The request contract, a reference endpoint you can clone, settlement and payouts.
All 9 pages →- I want to know it is safeSecurityHow keys, money and tool calls are protected, how to report a vulnerability, and the safe harbour for researchers.
- I want the termsLegalThe Terms of Service, Privacy Policy, Creator Agreement and the providers we use. Drafts, pending review by counsel.
How one call works#
The same five steps whichever side you are on, which is why both sets of docs describe the same boundary from opposite ends.
- The agent calls
An agent sends MCP JSON-RPC to the gateway with a developer key.
- The gateway meters
It verifies the key, checks the wallet and that key’s rolling 24-hour cap, and deducts the tool’s fixed price — all in one atomic operation.
- The charge is durable
It awaits the charge event onto a durable queue before contacting the creator, so a lost event can never become a free call.
- The creator answers
It forwards the request to the creator’s endpoint, signed, and streams the response back without inspecting or storing it.
- The ledger records it
A worker nets the charge into a five-minute rollup and posts a double-entry row to an append-only ledger.
If the creator fails before any byte reaches the agent, the charge is voided automatically. Once bytes have streamed, the charge stands.
Four things that shape everything else#
- Money is an integer, as a string.
Every amount is micro-USD in a JSON string, never a number — because a JSON number above 253 loses precision in a JavaScript parser before your code ever runs.
- Pre-funded, with no auto-top-up.
The balance a developer adds is the ceiling. A runaway agent can spend at most what someone already decided to give it.
- Tool-call contents 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.
- The ledger is append-only.
Database triggers refuse updates and deletes. A correction is a new entry, never an edit.