CLI, MCP, and skills for agents

This is how an agent fills a deck on app.cards.fast. Same account you study in.

Sign up first. The account is free. Free is one deck and one hundred cards. Then point the agent at that account.

What the product does, and why the inbox exists, is on Features. This page is the wiring.

CLI

bin/cards add --deck Spanish --front 'What is the infinitive for "to eat"?' --back comer --tags verbs --source "dinner conversation" --agent claude
bin/cards inbox
bin/cards mcp

add writes a card. inbox lists what is waiting for a human. mcp starts the Model Context Protocol server on stdio.

Other useful commands: accept, status, export, import, guide.

MCP

bin/cards mcp

Point Claude Code or Cursor at it. Use an absolute path to bin/cards.

{
  "mcpServers": {
    "cards.fast": {
      "command": "/absolute/path/to/cards.fast/bin/cards",
      "args": ["mcp"]
    }
  }
}

In Cursor, that block goes in mcp.json. In Claude Code, it goes in your MCP server config. Same shape.

Tools

• create_card / create_cards — write atomic cards (inbox by default)
• list_decks / create_deck
• search_cards / update_card
• get_inbox / accept_cards
• today_summary
• writing_guide

Prompts: write_atomic_cards. Resources: cards://writing-guide, cards://today, cards://inbox.

Skills and AGENTS.md

Drop AGENTS.md in a project so an agent prefers the CLI or MCP over clicking around. The atomic-card rules live in docs/card-writing.md:

1. One fact per card.
2. The front must stand alone.
3. Ask for recall, not recognition.
4. Keep the back short.
5. Do not write list cards.
6. Do not copy paragraphs.
7. Hold new agent cards for the inbox unless you asked for live cards.
8. Do not invent facts.

After the agent writes, you study. The manual is the human half of that.

Hosted MCP

A hosted MCP for ChatGPT, Claude.ai, and Grok is coming. It does not work yet. Do not configure a remote Cards.Fast MCP URL. bin/cards mcp is what you run today.

Pricing is the cap: one deck, one hundred cards, free. More than that is paid. If you already live in Anki or Mochi, Compare is the honest map.