# Hosts (/docs/api/gateway/hosts)

The relay that lets a phone run an operation on your desktop: presence stream, exec and result.

A host is a device that keeps `GET /v1/hosts/stream` open. Another device posts an `exec`; the gateway relays it over that stream and blocks until the host posts the result or the timeout fires. Presence expires 45 s after the last heartbeat. This relay is best-effort and not part of the public sessions protocol spec. Walkthrough: [hosts guide](../../sessions/hosts.mdx).

Agents see which hosts are online through the MCP server tool `hosts_list` (read-only; `exec` is not exposed over MCP).

<OpenAPIPage document="./openapi/en/gateway.yaml" operations={[{path: '/v1/hosts',method: 'get'},{path: '/v1/hosts/stream',method: 'get'},{path: '/v1/hosts/{deviceId}/exec',method: 'post'},{path: '/v1/hosts/exec/{reqId}/result',method: 'post'}]} />