Definition
An intermediary that fronts one or more MCP servers and centralizes concerns such as routing, authentication, authorization, tool filtering, rate limits, schema normalization, logging, or audit. A host connects to the gateway as though it were an MCP server; the gateway forwards or transforms allowed traffic to downstream servers.
This can reduce duplicated security and operations work across many integrations. A gateway can enforce tenant policy, hide internal topology, attach identity, block disallowed tools, and provide one place to observe traffic. It may also translate between transports or aggregate capabilities, though aggregation raises naming, trust, and failure-isolation questions.
Not a standard MCP role
The core MCP architecture defines hosts, clients, and servers. Gateway is a deployment pattern used by products and platform teams, not a required protocol participant with one normative behavior. Document whether a particular gateway terminates authentication, rewrites schemas, stores content, makes policy decisions, or merely routes bytes.
Distinguish it from nearby terms
A reverse proxy forwards application traffic. An API gateway applies cross-cutting controls to APIs. An MCP gateway applies a similar pattern to MCP connections and primitives. An MCP host gateway may additionally mediate model access, user consent, or context entering the host; product names alone do not establish those responsibilities.
Check your understanding
Your gateway logs every tool argument for audit. One downstream tool handles secrets. Has centralization improved security? Only if logging redacts or protects sensitive values, access to the gateway is controlled, and a gateway compromise does not grant broad downstream authority.