Connect J-Quants to Codex
Query J-Quants directly from Codex. Arlet links the two through one MCP connection and takes care of API keys.
This server connects your AI client to J-Quants API V2, the official market data API operated by JPX Market Innovation & Research (Japan Exchange Group). It provides pro-grade Japanese equities data collected directly from the exchange.
Key features:
- Look up listed companies (name, sector, market segment) by issue code or by company-name keyword.
- Fetch daily OHLC bars (open/high/low/close, volume, turnover, and split-adjusted figures) for any listed stock, over a date range.
- Fetch quarterly financial summaries built from TDnet earnings reports (kessan tanshin).
- Check upcoming earnings announcement dates and the trading calendar (market holidays).
Using the API requires a J-Quants account and an API key issued from the J-Quants dashboard. A free plan is available (data is delayed; paid plans unlock fresher data, longer history, and higher rate limits - the free plan allows 5 requests per minute). Set the key as JQUANTS_API_KEY in your Arlet environment variables.
How to connect J-Quants to Codex
- 1
In the Arlet dashboard, open Data tools, find J-Quants, set the API key issued by J-Quants and switch it on.
- 2
In your terminal, run codex mcp add arlet --url https://mcp.arlet.dev/mcp/ to add Arlet as an MCP server.
- 3
Codex detects OAuth support and opens your browser. Sign in with Google and click Allow on the consent screen.
- 4
Once connected, both the CLI and the IDE extension can call Arlet tools (the configuration is shared).
If the browser does not open, run codex mcp login arlet to redo the authentication.