Connection guide

Give your assistant access
to your decks.

The connector lets Claude or ChatGPT create and maintain your Grandmaster Flash library. You add it once, then use it in a conversation.

Sign in with the same email address as the mobile app. You’ll receive a one-time code and approve access to your private account.

The server address

Use this address for either assistant:

https://api-production-a2e2.up.railway.app/mcp

01 · Claude

Add a custom connector.

Open Claude on the web. Go to Customize → Connectors (in some versions, Settings → Connectors).
Choose + Add → Add custom connector. Name it Grandmaster Flash and paste the server address above. Choose Continue.
Keep OAuth authentication. If Claude asks how to identify its OAuth client, choose Register automatically. This server registers the connection for you; leave custom client credentials and request headers empty.
Finish adding the connector and choose Connect or Sign in now. Enter your app email, use the code from your inbox, and approve the account access.
Start a chat. Open the + menu, choose Connectors, and enable Grandmaster Flash for that conversation.

On Team or Enterprise, an owner may need to add the connector under Organization settings first. Claude’s current connection guide.

02 · ChatGPT

Create a custom MCP app.

Check your workspace first. Creating and editing decks needs MCP write actions. OpenAI currently documents full custom MCP support for eligible Business, Enterprise, and Edu workspaces on ChatGPT web. Pro’s read/fetch access alone cannot create decks. If your workspace doesn’t have this access, use Claude.

Open ChatGPT on the web in the workspace you want to use. An admin may need to allow custom MCP apps and give you developer access.
Enable Developer mode in Settings → Apps → Advanced settings, where available. Business admins can also enable it while creating an app in Workspace settings → Apps → Create.
Go to Apps → Create. Name the app Grandmaster Flash, paste the MCP server address above, and select OAuth authentication. Leave optional custom client credentials blank.
Choose Scan Tools (or the available create/connect action). Sign in with your app email and one-time code, then approve access. Finish creating the app after the tool scan.
Start a normal chat and select Grandmaster Flash from the tools/apps menu, or @mention it. Select it again when a later message needs to read or change your library. Approve the requested actions when prompted.

An admin can publish the draft to other workspace members. Setup labels and availability can change; check OpenAI’s current MCP guide if you don’t see these options.

03 · Your first deck

Ask for something you’ll use.

Once connected, try this:

Use Grandmaster Flash to create a deck of 15 everyday French phrases for talking with a tutor. Include English translations, a short example for each phrase, and French audio. Show me the content so I can check it.

Check what your assistant creates, then open the app and sync your library. Allow the deck and audio to finish downloading before going offline. Choose the deck and start studying.

Later, ask your assistant to correct a translation, add examples, or work through flagged cards. You can revoke the connection in the app under Settings → Assistants.

If you get stuck

My deck isn’t in the app.

Check that the assistant and app use the same email. Ask the assistant to list your decks to confirm it saved the content, then sync the app while online.

I can’t see the connector or its tools.

Check your plan and workspace permissions. Enable the connector for your message or conversation. If tools are stale, reconnect in Claude or ask your ChatGPT workspace admin to refresh the app’s tools.

My sign-in code hasn’t arrived.

Check spam and that the email address is correct. Request a new code if the old one expired. Never send us the code.

Audio doesn’t play offline.

Audio needs to finish downloading while you’re online. Use Settings → Downloads → Retry downloads if a download failed.