A founder tells me they're "shopping for agent infrastructure," and within two sentences it's clear they don't know whether they want a catalog or a control plane. They've bookmarked a registry and a gateway, assume the two overlap, and expect one of them to do the other's job. It never does.
If you read one line: a registry answers what agents and tools exist and how do I find them; a gateway answers how does traffic to those tools get routed, authenticated, rate-limited, and observed at runtime. Discovery versus control. Different layers, different day, different vendor list.
What a registry actually does#
A registry is a discovery and catalog layer. It's the index that says: this MCP server exists, here's who published it, here's the install command, here's the version. It's a build-time concern — you consult it when you're deciding what to wire up, not while a request is in flight.
The official MCP Registry is the canonical example: an open, community-run meta-registry that stores metadata and install instructions while the actual code lives in npm, PyPI, or a container registry. Directories like Smithery sit on top as storefronts — Smithery alone indexes over 7,000 servers. In the managed world, AWS Agent Registry does the same job inside AgentCore, cataloging MCP servers, A2A agents, and skills with governance metadata. All of them answer the same question: what's out there, and can I trust its provenance?
A registry does not route your traffic. It won't authenticate a call, enforce a quota, or hand you a log. Ask it to and you'll be disappointed — that was never its job.
What a gateway actually does#
A gateway is a runtime control plane and proxy. It sits in the request path, in front of your tools, and every call goes through it. That position is the whole point: it's where you enforce auth, rate limits, RBAC, and policy, and where you emit the traces and logs that tell you what actually happened.
agentgateway is a clean example — an Apache-2.0 proxy, now a Linux Foundation project, that fronts MCP and A2A traffic with JWT/OAuth auth, a policy engine, rate limiting, and OpenTelemetry output. MetaMCP aggregates many MCP servers behind one authenticated endpoint with pluggable middleware. If you want the head-to-head, we covered MCP gateways compared: ContextForge vs agentgateway vs MetaMCP separately.
A registry is a map; a gateway is the toll booth every car has to pass through.
Which problem do you actually have?#
Here's the tell, and it's the one non-obvious thing worth internalizing: the two failures hurt in completely different places.
- You feel a missing gateway as a security and observability gap. Every tool carries its own credentials. There's no shared rate limit, so one runaway agent can hammer a downstream API. When something breaks at 2 a.m., there's no single audit trail. This pain shows up in incidents.
- You feel a missing registry as a discovery and duplication gap. Two engineers build the same Notion MCP server because neither knew the other existed. Nobody can answer "what tools do we even have?" This pain shows up in planning and code review, quietly, over months.
If your pain is runtime — leaks, overages, blind spots — you want a gateway. If your pain is organizational — sprawl, duplication, provenance — you want a registry. We went deeper on the discovery side in agent registry vs MCP registry for discovery.
The conflation is understandable, because a few products ship both jobs in one box. ContextForge bills itself as a gateway and a registry; AWS AgentCore pairs a Registry with a Gateway as separate services. That's convenient, but it's precisely why founders assume one product's registry is a substitute for another product's gateway. It isn't — a gateway's built-in catalog only lists what passes through that gateway, not a neutral, org-wide index.
Adopt them in this order#
For most solopreneurs, the sequence is not a toss-up.
- Gateway first. The day you have three or more tools in production, the runtime pain arrives. Put a gateway in front, centralize the keys, set rate limits, turn on tracing. You now have one governed endpoint and one log.
- Registry second. Add it when discovery starts costing you — when duplication, "does this exist already," and provenance questions eat real time. That's usually a team-size problem, not a solo one.
The reason discovery can wait is that with a handful of tools you already know what you have; the catalog buys you little. The reason the gateway can't wait is that the first leaked credential or unbounded loop is an incident, not an inconvenience. As we've argued, discovery is the new distribution — so a registry earns its keep the moment other people need to find your tools, which is a later, better problem.
Buy the layer whose pain you can feel today. The other one will announce itself when it's ready.
