Open Ephemeris is a production-grade MCP server that gives Claude, ChatGPT, Gemini, Cursor, and any MCP-compatible agent direct access to real astronomical data. Over 100 tools cover the full range of astrological traditions: natal chart calculation, transit and progression forecasting, synastry, astrocartography ACG lines, Human Design body graph, BaZi four pillars, eclipse windows, lunar phases, planetary hours, and fixed star positions. All positions are computed at request time from JPL DE440 — accurate to arc-second precision. No hallucinated positions. No astronomy math in your application code. Free tier available.