What's the Difference Between Custom, Proxied, and Hosted MCP Servers (and How Do Credentials Work When Sharing an Agent)?

Last updated: June 18, 2026

Beyond Gumloop's 50+ built-in app integrations, there are three ways to bring an MCP server into Gumloop: a Custom MCP server (you connect any MCP URL yourself), a Proxied MCP server (an admin routes an external server through Gumloop's managed proxy), and a Hosted MCP server (your org deploys its own server code on Gumloop's infrastructure). They differ in who manages the connection and whose credentials are used when someone else runs your shared agent.

Quick Comparison

Type	What it is	Who sets it up	Where
Custom MCP server	You point Gumloop at any external MCP server URL	Any user	Settings → Apps (Credentials)
Proxied MCP server	An external MCP server routed through Gumloop's managed proxy	Organization admin	Settings → Organization → Proxied MCPs
Hosted MCP server	An MCP server your org builds in a GitHub repo and Gumloop deploys for you	Organization admin (Enterprise)	Settings → Organization → Hosted MCPs

1. Custom MCP Server

You connect any MCP-compatible server by entering its URL. This is the simplest option and the right choice when you just want to plug your own (or a third party's) MCP endpoint into your agent.

You add it in Settings → Apps by searching for MCP Server, clicking Add MCP Server, and entering:

URL — your server's endpoint (must use HTTPS)
Label — a name like slack-mcp-server
Access Token / API Key — sent as an Authorization: Bearer <token> header, if your server needs it
Additional Header — any custom header in Header-Name: value format

If your server uses OAuth, Gumloop detects it from the URL and opens an OAuth popup to connect. Once saved, the server appears under the Custom MCP section of your agent's Tools panel.

The server must be publicly accessible over HTTPS and use Streamable HTTP or SSE transport — local and localhost servers are not supported.

For the full walkthrough, see A Service I Use Published an MCP Server but I Don't See It in Gumloop — How Do I Connect It?

2. Proxied MCP Server

A proxied MCP server is an external MCP endpoint that an organization admin registers once, so all traffic flows through Gumloop's managed proxy. Use this when your org wants a single, governed place to connect and audit an outside MCP server instead of having each person paste a URL.

An admin sets it up in Settings → Organization → Proxied MCPs and chooses one of three authentication methods: None, API Key, or OAuth 2.0. That choice determines how credentials behave for everyone who uses it (see the credentials section below).

3. Hosted MCP Server

A hosted MCP server is one your organization builds and deploys on Gumloop's own infrastructure. You write the server code in a GitHub repository, and Gumloop handles building, deploying, monitoring, and routing requests to it. Use this when you want to run your own custom MCP server without standing up separate hosting.

Hosted MCPs are an Enterprise feature managed in Settings → Organization → Hosted MCPs. Access to each server is controlled through your organization's custom roles. If you don't see this section, contact your organization admin.

Whose Credentials Are Used When You Share Your Agent?

This is the part that trips people up. Gumloop never silently shares one person's personal login with everyone. When a teammate runs your shared agent, what happens depends on the server type:

Server type	Whose credentials run the tool	What the end user must do
Custom MCP (personal credential)	The credential found in the chatting user's own scope	Each user adds their own copy of the Custom MCP credential
Custom MCP (team credential)	The one shared team credential	Nothing — everyone on the team uses the shared connection
Proxied MCP — auth None or API Key	One org-level credential the admin configured	Nothing — all users share it
Proxied MCP — auth OAuth	Each user's own OAuth token	Each user connects once via OAuth
Hosted MCP	Each user's own connected credentials for the downstream services	Each user connects the services the server talks to

The key takeaways:

A Custom MCP credential stored as personal only works for you. To let your team use it on a shared agent, store it as a team credential when you connect it, or have each teammate add their own. See the team vs personal note in the credentials docs.
A Proxied MCP is shared centrally only when the admin chose None or API Key auth. If it uses OAuth, each person still authenticates individually.
For Hosted MCP and per-user OAuth cases, a user who hasn't connected yet sees an unauthenticated status and a prompt to connect before they can use the tool.

To control which specific connected account an agent uses, see How Do I Assign a Specific Gmail (or Other Integration) Account to a Specific Agent?

Which One Should I Use?

Just connecting one external or internal MCP server for yourself or your team → Custom MCP server.
Your org wants one governed, audited connection to an outside MCP server that everyone uses through a managed proxy → Proxied MCP server.
Your org wants to build and run its own MCP server code without managing separate hosting → Hosted MCP server (Enterprise).

Still Need Help?

If this didn't resolve your issue, reach out to support at support@gumloop.com.