# MCP Overview (/docs/mcp/overview)



MCP apps expose callable **tools**, URI-addressable **resources**, and reusable **prompts** through one gateway endpoint. Protocol version `2026-07-28`, stateless: no sessions, no initialize handshake, no `Mcp-Session-Id`, no GET/DELETE endpoints. SSE streams are per-request on POST; close = cancel.

## At a glance [#at-a-glance]

|                  |                                                                                               |
| ---------------- | --------------------------------------------------------------------------------------------- |
| Endpoint         | `POST /v1-beta/mcp/{username}/{appname}`                                                      |
| Required headers | `Authorization`, `Content-Type`, `MCP-Protocol-Version: 2026-07-28`, `Mcp-Method`, `Mcp-Name` |
| Billing unit     | Requests (per-call on usage-based pricing)                                                    |
| Start here       | [Buyer Guide](https://docs.openvoidnet.com/docs/mcp/buyer) to call · [Publisher Guide](https://docs.openvoidnet.com/docs/mcp/publisher) to publish    |

## Methods [#methods]

`server/discover` (capabilities first), `tools/list`, `tools/call`, `resources/list`, `resources/read`, `prompts/list`, `prompts/get`, `subscriptions/listen` (optional). Full shapes with examples live in the [Buyer Guide](https://docs.openvoidnet.com/docs/mcp/buyer).

## Rules that bite [#rules-that-bite]

* `MCP-Protocol-Version` must equal `_meta.protocolVersion` in the body, or the call fails `400 HeaderMismatch`.
* Every proxied request carries your publisher key (`vnp-sk-*`); validate it on every request.
* Billable `tools/call` responses meter one request; list/discover calls never bill.