MCP (Model Context Protocol)

Connect any MCP-compatible server to give Fours AI access to external tools and data.

Overview

The Model Context Protocol (MCP) is an open standard for connecting AI assistants to external tools and data sources. Fours’ MCP integration lets you connect to any MCP server that supports OAuth 2.1 authorization, giving Fours AI the ability to use tools from 75+ popular services --- or any custom MCP server you provide.

Once connected, Fours AI can discover and use all tools exposed by the MCP server. For example, connecting your Stripe MCP server lets Fours AI look up payments, manage subscriptions, and query billing data on your behalf.

Org-Level vs User-Level

Org-Level: Not applicable. MCP server connections are user-level only.

User-Level: Each user connects their own MCP servers with their personal credentials. Tools are available to that user’s Fours AI sessions.

Pre-Configured Providers

Fours includes a catalog of 77 pre-configured MCP servers. Select any provider from the catalog to connect instantly --- no manual URL entry required.

You can also connect any custom MCP server by entering its URL directly.

Authentication Methods

Fours connects to MCP servers with OAuth (PKCE) only. You sign in and approve access on the server’s own authorization page; Fours discovers the server’s OAuth configuration, registers itself as a client, and refreshes the token for you (see How It Works). The server must support OAuth 2.1, so a server that offers only client credentials or a static API key can’t be connected.

Create Integration

Connect via Catalog (OAuth)

1. Navigate to Settings > Integrations and scroll to Custom MCP Servers
2. Click Add MCP server
3. Under Popular MCP Servers, find the provider (e.g., Stripe, Linear, Notion) — search, or filter by category — and click + on its card. A provider with more than one endpoint lets you pick one on the card first
4. The provider’s authorization page opens in a new tab
5. Log in and approve access
6. Back in Fours, the dialog closes with MCP server connected successfully, and the server appears under Custom MCP Servers

Connect via Custom URL (OAuth)

1. Navigate to Settings > Integrations, scroll to Custom MCP Servers, and click Add MCP server
2. Enter your MCP server URL (e.g., https://mcp.example.com/mcp) in Remote MCP Server URL and click Connect
3. Fours automatically discovers the server’s OAuth configuration and opens its authorization page in a new tab
4. Follow the OAuth authorization flow
5. When it completes, the server appears under Custom MCP Servers

Connect Fours’ own MCP server

The catalog also lists Fours’ own MCP server — the one described in the MCP section — on a card the console still labels Suger. Connecting it gives your Fours AI sessions the Fours tools, and on this card you also choose how much of the server those sessions may use.

1. Navigate to Settings > Integrations and scroll to Custom MCP Servers.
2. Click Add MCP server.
3. In Connect a custom MCP server, find the Suger card (server https://apiv2.suger.cloud/mcp, category Marketplace).
4. Pick an Access level on the card, then click + and complete the authorization in the window that opens.

That window is the Fours console sign-in. If your organization signs in with single sign-on and the window stops before the Authorize Application screen — for example, on an error page — see Troubleshooting in the MCP setup guide.

• Once connected, the card shows the level you chose — for example Access: Read only. To change it, disconnect the server and connect it again with the level you want.
• Agents show the same level. In the integration list of an agent you own, and in the Insulin assistant’s own settings, this server’s row reads Read-only, Edit or Full — for Read only, Read & write and Read, write & delete — with nothing to change beside it: the level is set on this card, and Fours’ MCP server enforces it on every request.
• A connection made before the Access choice existed counts as Read only, so it gets no write tools until you reconnect it with wider access.
• Access only narrows the tools on offer. It never widens what your Fours account may do: Fours still checks your permissions on every call.
• Only this card has an Access choice. Other MCP servers expose whatever tools they offer, and each agent that uses one can narrow it with its own Read-only, Edit or Full setting — see Agent access levels.

For what each tool does, see Supported Tools.

Verification

There is no separate Verify step: a server counts as connected once its authorization completes, and Fours AI can use its tools from then on. If the authorization doesn’t finish within five minutes, the dialog stops waiting and says the connection timed out — try again. A server whose connection didn’t complete shows a Delete button instead of its ⋯ menu; delete it and add the server again.

Edit Integration

Editing is not supported. To connect a different account — or, for Fours’ own server, a different Access level — disconnect the server and add it again.

Delete Integration

To remove a server, open its ⋯ menu under Custom MCP Servers and choose Disconnect. This removes the connection and its stored credentials from Fours.

How It Works

OAuth Discovery

For OAuth-based connections, Fours automatically discovers the provider’s authorization endpoints using open standards:

1. RFC 9728 (Protected Resource Metadata) --- determines which authorization server protects the MCP endpoint
2. RFC 8414 (Authorization Server Metadata) --- retrieves the authorization, token, and registration endpoints
3. RFC 7591 (Dynamic Client Registration) --- registers Fours as an OAuth client if no pre-registered app exists

This means most MCP servers work out of the box without any manual endpoint configuration.

Token Refresh

Tokens are refreshed automatically before expiry using the refresh token. If no refresh token was issued, you must reconnect when the token expires.

One Connection Per Provider

Each user can have one MCP connection per provider. To switch accounts or credentials, disconnect the existing integration first, then reconnect.

Fours AI Tools

MCP integrations do not provide a fixed set of AI tools. Instead, when you connect an MCP server, Fours AI automatically discovers all tools that the server exposes. The available tools depend entirely on the provider.

For example:

• Stripe MCP might expose tools for querying payments, managing customers, and creating invoices
• Linear MCP might expose tools for creating issues, updating projects, and searching tickets
• Notion MCP might expose tools for reading pages, creating databases, and searching content

Fours AI asks the server for its current tools each time it starts work, so the list follows whatever the provider’s MCP server offers and changes as the provider updates it.