Everything the gateway reads from you, returns to you, and refuses to pass on.
What you send#
| Header | Required | Meaning |
|---|---|---|
X-Nexus-Api-Key | Yes | Your nx_dev_ key. Never forwarded to a creator |
Content-Type | Yes | application/json for JSON-RPC |
Idempotency-Key | No | Makes a retry safe. See idempotency |
Authorization | No | The tool's own credential, forwarded untouched. Refused if it carries an nx_dev_ token |
Accept, MCP-Protocol-Version, Mcp-Session-Id | No | Forwarded so a creator's MCP server can negotiate with your real client |
What you get back#
| Header | When | Meaning |
|---|---|---|
X-Correlation-ID | Always | The id for this call. Quote it if you ask us about a specific request |
X-Nexus-Error | On a refusal | The error code, also in the body |
X-Nexus-Required-Amount | On a 402 | The shortfall, in integer micro-USD as a string |
X-Nexus-Currency | On a 402 | USD |
Retry-After | On a 429 | Seconds to wait |
What is never forwarded#
What the creator receives#
For completeness, since it explains what a tool can and cannot know about you: the creator gets a correlation id, a signed envelope proving the request came from us, their own creator key, your pass-through Authorization if you sent one, and the MCP negotiation headers. They do not get your key, your account, your wallet or your balance.