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How it works

How do I plug the Quantblocks MCP into Claude or ChatGPT?

The Quantblocks MCP server lets AI assistants like Claude or ChatGPT talk to your account directly — they can list your strategies, build indicators, run backtests and pull the results back. All you need is an API key and a small config file. The snippet above is the full configuration for Claude Desktop.

claude_desktop_config.json 
{
  "mcpServers": {
    "quantblocks": {
      "type": "http",
      "url": "https://mcp.quantblocks.io/mcp",
      "headers": {
        "Authorization": "Bearer qb_sk_DEIN_API_KEY"
      }
    }
  }
}

  1. Pro account

    MCP is a Pro-only feature. Free accounts cannot use it — the connection is rejected on the first tool call. If you're not on Pro yet, upgrade under Settings — Subscription.

  2. Create an API key

    Generate a Quantblocks API key under /settings/api-keys.

Connect Claude Desktop

  1. Install Claude Desktop

    Download the latest Claude Desktop app from claude.ai/download and sign in with your Anthropic account. MCP support is built in.

  2. Open Settings

    In the system menu bar click Claude — Settings (not the in-window account settings), open the Developer tab and click Edit Config. This opens the configuration file in your default editor.

  3. Locate the config file

    If the file does not exist yet, Claude creates it for you when you click Edit Config. The default paths are:

    • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
    • Windows: %APPDATA%\Claude\claude_desktop_config.json
    • Linux: ~/.config/Claude/claude_desktop_config.json

  4. Paste the snippet and restart

    Copy the JSON snippet above into the file, replace qb_sk_DEIN_API_KEY with your actual API key, save the file and quit Claude Desktop completely (don't just close the window). On restart, Quantblocks shows up in the tools menu at the bottom right of the chat.

Connect Claude Code CLI

Claude Code is the terminal version. Instead of editing a JSON file, you add the server with a single command:

claude mcp add --transport http quantblocks https://mcp.quantblocks.io/mcp \
  --header "Authorization: Bearer qb_sk_DEIN_API_KEY"

Then verify with:

claude mcp list

Connect ChatGPT

  1. As of April 2026

    ChatGPT now supports remote MCP servers via the Connectors menu in Settings — primarily for Deep Research and MCP-based apps. Availability still depends on your plan and region. If you're on ChatGPT Pro or Business, open Settings — Connectors and add https://mcp.quantblocks.io/mcp as a custom connector. ChatGPT will ask for a Bearer token during connection — paste qb_sk_DEIN_API_KEY there.

  2. If your plan doesn't expose custom connectors yet

    Then Claude (Desktop or Code) is the easier path today — Quantblocks works there with no workaround. We'll update this page as OpenAI rolls custom MCP connectors out to all plans.

What you can ask

Once the server is connected, Claude understands sentences like these naturally — you don't need to learn tool names:

  • List all my strategies.
  • Create a new indicator called RSI-14 that computes RSI over 14 periods.
  • Backtest my SMA-Crossover strategy from January 1st 2024 to today with 10,000 USD starting capital.
  • Which symbols and timeframes are available for backtests?
  • Show me the performance metrics of my most recent backtest.

When something doesn't work

  1. Invalid API key

    The key is wrong, expired, or revoked. Check under /settings/api-keys that it still exists and copy it freshly into the config. Make sure the Bearer prefix is in front of the key.

  2. MCP access requires the Pro plan

    The key belongs to a Free account. MCP is Pro-only — upgrade your subscription and the connection works immediately without a new key.

  3. Connection refused / server not found

    Verify the URL — it must be exactly https://mcp.quantblocks.io/mcp (with /mcp at the end, not just the domain). For Claude Desktop a full app restart after every config change usually fixes lingering issues.

  4. Quantblocks doesn't show up in the tools menu

    The JSON file likely has a syntax error (often: a missing comma or wrong quote character). Validate it in a JSON linter. For Claude Desktop, logs live at ~/Library/Logs/Claude (macOS) and %APPDATA%\Claude\logs (Windows).