Connect Claude or ChatGPT to your Cefra dictionary

Server address

Paste this address where your assistant adds a custom connector. It is the same for Claude and ChatGPT.

Connected Cefra before November 2026 with an address ending in /mcp? That address no longer works: remove the old connector in your assistant and add Cefra again with the address above.

Before you start

• A free Cefra account with at least one language you are learning. Languages are added in Cefra, not through the assistant.
• An assistant that lets you add a custom connector, that is a remote MCP server with sign-in.

Connect Claude

1. In Claude, open Settings → Connectors and choose to add a custom connector.
2. Name it, for example Cefra, paste the server address and save.
3. Select Connect. Claude opens the Cefra sign-in page in your browser.
4. Sign in, check the consent screen and allow access. Back in Claude, the Cefra tools are available in your chats.

Connect ChatGPT

1. In ChatGPT, open Settings → Apps & Connectors. Adding your own connector may require developer mode in the advanced settings.
2. Create a connector named, for example, Cefra, paste the server address and choose OAuth for authentication.
3. ChatGPT opens the Cefra sign-in page. Sign in, check the consent screen and allow access.
4. In a new chat, turn on the Cefra connector and ask, for example: “Create a set Travel with 20 everyday German words.”

Signing in and the consent screen

• Cefra has no passwords: you sign in on Cefra’s own page with a code sent by email or with a social account. The assistant never sees how you sign in.
• A new account first chooses the language it learns: without a language pair the assistant has nothing to work with.
• The consent screen shows the domain Cefra sends you back to. For Claude and ChatGPT it is marked as verified. That only means the access goes to the Claude or ChatGPT service, not that you started the connection.
• Continue only if you pressed “connect” yourself: access goes to the assistant account the connection was started from, and someone could send you a link from their own account.
• Apps Cefra does not know are marked “unverified app”, and apps on your computer “local app”. Their name is shown as the app states it.
• The consent screen appears on every connection, including when you reconnect.
• After each new connection Cefra emails you the app, its domain and its permissions, with a link to disconnect it.

Permissions

On the consent screen you choose what the assistant may do. You can allow less than it asks for.

Read your dictionaryvocab:read

Your language pairs, sets and words, and search in your words and in the public catalogue.

Change your dictionaryvocab:write

Create and edit sets, add words (up to 50 at a time), edit words, add a word to a set, and copy public sets and words.

Delete from your dictionaryvocab:delete

Remove a word from a set, delete a word or a set. Unticked by default: allow it only if you want the assistant to delete. Deleting a set takes two steps: the assistant first sees what the set contains and then confirms.

“Stay connected” (offline_access) keeps the connection without signing in again. On its own it gives no access to your dictionary.

What the assistant can do

• Work only with your own private sets and words and read the public Cefra catalogue.
• Report on every word it adds: created, added to the set, already in the set, invalid, or over the daily limit.
• Attach a word you already have to another set without counting it as a new word.
• Copy a public set or word. Copying the same set again returns the copy you already have.

What it cannot do

• See or change other people’s data.
• Change your profile or account, or add languages to learn.
• Read or change your training progress.
• Add images or audio, or links to pictures and sounds.
• Extract words from photos.
• Delete in bulk or delete by a search.
• Restore deleted data. Support can do that within 30 days.

Limits

The limits are the same for every account, premium included, and apply only to what an assistant does. The Cefra website and app work as before.

• Per day, across all your assistants (resets at midnight UTC): 300 new words, 300 edits to words and sets and 100 deletions.
• In total: 200 sets and 20,000 words. Only data you have not deleted counts. The limit stops creating more through an assistant and never touches what you already have.
• Per minute: 60 requests, of which at most 20 changes, for each assistant, and at most 120 requests, of which at most 40 changes, for your account.
• One request returns at most 100 items. The assistant fetches the next page itself.
• A public set larger than what is left of the day’s new words is not copied in part. Copy such a set on the website.

Security questions