Cirello MCP serverConnect your flashcards to AI assistants.

What it is

MCP, the Model Context Protocol, is an open standard that lets an AI assistant use tools in another product. Cirello runs a remote MCP server, so an assistant that supports MCP can work with your Cirello library when you ask it to. There is nothing to install, nothing to host yourself and no API key to copy around.

The server address is:

https://api.cirello.app/mcp

It uses the Streamable HTTP transport. Sign-in is standard OAuth 2.1 with dynamic client registration, so a client that supports remote MCP with OAuth only needs the URL above. You sign in to Cirello in your browser and approve a consent screen. The assistant never sees your Cirello password.

For the short announcement and the thinking behind it, read Introducing Cirello MCP.

What you can ask an assistant to do

The assistant gets a set of tools, and each tool does one clear job. In practice, that means you can ask for things like:

• "Turn these 20 vocabulary pairs into a deck called Spanish A2." The assistant creates the deck and adds the cards, up to 50 cards per request.
• "What is due today, and how is my streak?" It reads today's review queue and your statistics.
• "Find duplicate cards in my library and show me the groups." It scans for cards with the same front, back or both. You decide whether to merge them or dismiss the group.
• "Split this overloaded card into three." A plain-text card becomes two to ten smaller cards that keep its review progress. The idea is covered in how to write good flashcards.
• "Search my library for cards that mention mitochondria." It does a text search across fronts, backs and notes, optionally inside one deck.
• "Move these cards to my Biology deck", "Rename this deck" or "Create a folder for next semester." It moves cards between decks and creates or edits decks and folders.
• "Snooze this card until next week." It pushes the next review out without counting as a review.

There are 16 tools in total. Reading tools are the library overview, card search, duplicate finder, today's queue and statistics. Writing tools create and edit cards, move cards, snooze, and create folders and decks. Cleanup tools merge duplicates, dismiss false duplicates and split cards. One tool deletes cards permanently.

What it cannot do

The assistant cannot run a review session or grade your cards. There is no review tool. It can read what is due and snooze a card, but the reviewing itself happens in Cirello, where it is scheduled by FSRS-6. Built-in decks are read-only, so the assistant cannot edit or add cards to them.

Set it up

Menus and settings in AI products change often, so the steps below are kept short. Where a vendor's documentation says something specific, it is followed here; otherwise the instruction is generic.

Claude (claude.ai and the desktop app)

Add Cirello as a custom connector:

1. Open Customize > Connectors.
2. Click + Add, then Add custom connector.
3. Enter a name, such as Cirello, and the URL https://api.cirello.app/mcp, then click Continue.
4. Review the detected authentication settings, then click Add.
5. Sign in to Cirello when the browser opens, and approve the permissions you want to give.

On Team and Enterprise plans, an owner adds custom connectors under Organization settings, and members then connect to it from Customize > Connectors. Anthropic's article on custom connectors has the current details.

Claude Code

Run this in your terminal:

claude mcp add --transport http cirello https://api.cirello.app/mcp

Then open Claude Code, type /mcp, select Cirello and follow the browser steps to sign in.

ChatGPT

Add a custom or remote MCP connector in ChatGPT's settings, paste https://api.cirello.app/mcp as the server URL, choose OAuth for authentication, and sign in to Cirello when the browser opens. The exact menu names and which plans can add custom connectors have changed over time and may depend on your plan or workspace settings, so check OpenAI's current help pages for where it lives in your account.

Cursor

Add Cirello to your mcp.json, either .cursor/mcp.json in a project or ~/.cursor/mcp.json for all projects:

{
  "mcpServers": {
    "cirello": {
      "url": "https://api.cirello.app/mcp"
    }
  }
}

Cursor supports OAuth for servers that require it, so follow the sign-in prompt for Cirello when it appears.

Any other MCP client

Look for an option to add a remote or custom MCP server, paste https://api.cirello.app/mcp, choose HTTP or Streamable HTTP as the transport, and sign in when the browser opens. If your client only supports local servers, it cannot connect to Cirello today.

Permissions and privacy

You decide what each connection may do. On the consent screen you can switch individual permissions on or off, and there are presets for the common cases:

• View folders, decks and cards.
• View due cards, statistics and streak.
• Create and edit cards, and move them between decks.
• Create and edit decks and folders.
• Merge duplicates and split cards.
• Delete cards. This is off unless you switch it on.

Tools you did not permit are not exposed to the assistant at all. Changes the assistant makes are saved to your account exactly as if you made them in the app.

Your password, email address, account settings, sign-in sessions and images are never sent to the assistant. Depending on your request, it can see things like folder and deck names, card text, each card's learning state and due date, your review queue and your statistics. Access tokens last one hour, refresh tokens rotate and expire after 30 days, and requests are rate-limited per user.

Once data reaches an assistant, the company that runs it processes it under its own terms, so check that provider's settings before connecting. The full details are in section 6 of the privacy policy.

Disconnecting

In the Cirello web app, go to Account - Security - Connected apps and press Remove next to the app. Access ends immediately and its tokens are deleted. You can connect it again later.

Good to know

Cirello is a web app today, and the MCP server is part of the free beta. An assistant can write cards for you, but what is worth remembering is still your decision. Skim what it creates, and keep cards small and clear. If you are not sure how many to add, how many flashcards to review per day is a useful read before you ask for a hundred.