How to Connect ChatGPT to an MCP Server
ChatGPT supports MCP (Model Context Protocol) servers. That means you can connect it to your notes, calendar, database, or any other service that speaks the protocol. There are two ways to add MCP to ChatGPT: install from the Apps Directory in one click, or add it manually via developer mode.
Not sure which path you need? If the server is already published in the Apps Directory (Hjarni, Notion, Linear, and others), use that. It is one click and needs no settings changes. Use developer mode for any custom, self-hosted, or beta MCP server that is not in the directory yet.
What you need
- A ChatGPT account. Apps Directory connectors work on any paid plan. Developer mode is available on Plus, Pro, Business, Enterprise, and Education.
- The MCP server you want to connect. Either listed in the ChatGPT Apps Directory (one-click install, like Hjarni), or available at a URL like
https://hjarni.com/mcp(developer mode).
MCP support in ChatGPT is currently rolling out and available on the web.
Option 1: Install from the ChatGPT Apps Directory
This is the fastest path. If the MCP server is published in the Apps Directory, ChatGPT handles the connection for you and no developer mode is needed.
Hjarni is in the Apps Directory. Open Hjarni on chatgpt.com, click Connect, sign in. That's it.
Step 1: Open the app page
- Open the direct app link (for Hjarni, that's chatgpt.com/apps/hjarni)
- Or open ChatGPT, click Apps in the sidebar, and search for the service you want
Step 2: Connect and sign in
- Click Connect
- Complete the OAuth sign-in for your account
- Enable sync if ChatGPT prompts for it
Step 3: Use the app in a conversation
- Start a new conversation
- Open the + (plus) menu and select the app, or invoke it with an @ mention
- ChatGPT can now call the server's tools. Write actions require your approval before they run.
Option 2: Add a custom MCP server via developer mode
If the server you want isn't in the Apps Directory (a self-hosted server, an internal tool, or a project still in beta), use developer mode. You create an "app" linked to your MCP server URL, then turn it on when you need it.
Step 1: Enable developer mode
- Open ChatGPT and go to Settings > Apps
- Scroll to Advanced settings
- Toggle Developer mode on
Step 2: Create an app from your MCP server
- In the developer mode settings, click Create app
- Enter your MCP server URL (e.g.
https://hjarni.com/mcp) - Complete the OAuth authentication flow if the server requires it
- Review the available tools and toggle on the ones you want
Step 3: Use the app in a conversation
- Start a new conversation
- Click the + (plus) menu and choose Developer mode
- Select the apps you want ChatGPT to use
- ChatGPT can now call the server's tools. Write actions require your approval before they run.
What ChatGPT can do with MCP
Once connected, ChatGPT can use whatever tools that server offers. For example, when connected to a knowledge base like Hjarni, ChatGPT can:
The specific capabilities depend on the MCP server. Each server exposes its own set of tools.
Verifying the connection
Start a new conversation and ask ChatGPT to use one of the server's tools. For example, if you connected Hjarni:
"What notes do I have in Hjarni?"
ChatGPT should respond with your notes or confirm it has access. If you see tool calls in the response, the connection is working.
Troubleshooting
The app does not appear in the Apps Directory
The directory is rolling out gradually. If you can't find it, open the app's direct link (for Hjarni: chatgpt.com/apps/hjarni) or fall back to developer mode.
ChatGPT says it cannot connect
For Apps Directory installs, sign out and back in and try Connect again. For developer mode, verify the MCP server URL is entered correctly and that you completed the OAuth flow. Try removing the app and adding it again.
ChatGPT does not see your data
Make sure the app is enabled for the current conversation. Open the + menu (or Developer mode for custom servers) and select the app. Also check that the right tools are toggled on in the app settings.
Developer mode does not appear
Developer mode is available on Plus, Pro, Business, Enterprise, and Education plans (web only). Check your plan in ChatGPT settings. If the server you want is in the Apps Directory, you don't need developer mode at all.
Try it with Hjarni
Hjarni is a knowledge base with a built-in MCP server. Connect it to ChatGPT and stop re-explaining yourself. Your AI reads your notes directly.
Hjarni is in the ChatGPT Apps Directory. Click Connect, sign in, done.