# open-ephemeris [Health: Active] **Category:** πŸš€ Aerospace & Astrodynamics **Repository:** https://github.com/openephemeris/openephemeris-MCP **GitHub Stars:** 5 **npm Downloads (last month):** 1937 **Views:** 2 **Installs:** 0 **Upvotes:** 0 **Directory Page:** https://allmcps.com/mcp/open-ephemeris ## Description Sub-arcsecond ephemeris and astrology on NASA JPL DE440: natal, transits, eclipses, Human Design. ## Tools Capabilities this server exposes over MCP: - **explore_natal_chart** β€” Use this when the user asks 'show me my birth chart', 'what's my rising sign', 'my big 3', 'what's my sun, moon and rising', 'what sign is my Moon / Venus / Mars in', 'what does my chart say about my career / love', 'read my chart', or shares birth details and wants to explore them β€” any natal / birth-chart / astrology-chart request. Returns an interactive chart wheel rendered inline (Claude and ChatGPT; text summary elsewhere) where any planet, house or aspect line can be clicked for interpretation, with switchable house systems. The birthplace can be given as `location` (a place name β€” resolved server-side) or as coordinates, together with the birth date and local time and its zone. CREDIT COST: 1 credit per call (+1 to resolve a place name). - **explore_human_design** β€” Use this when the user asks 'what's my Human Design', 'am I a Generator / Projector / Manifestor / Reflector', 'show my bodygraph', 'what's my HD type and profile', 'what's my strategy and authority' or 'what's my incarnation cross'. Returns an interactive bodygraph (inline in Claude and ChatGPT; text summary elsewhere) showing defined/undefined centers, active gates, channels, Type, Profile, Authority and Incarnation Cross, with any center or gate clickable for interpretation. Birthplace may be a place name (`location`). CREDIT COST: 4 credits per call (2 chart + 2 render; +1 to resolve a place name). Human Design was originated by Ra Uru Hu; OpenEphemeris is an independent calculation service, not affiliated with Jovian Archive. - **explore_human_design_transit** β€” Use this when the user asks 'what are today's Human Design transits for me', 'what gates are being activated for me right now', 'which channels does this transit complete in my chart' or 'how is the current sky affecting my bodygraph'. Returns an interactive overlay bodygraph (inline in Claude and ChatGPT; text summary elsewhere) highlighting the channels the transit temporarily COMPLETES with the natal chart and any centers it newly defines, for now or a chosen datetime. Birthplace may be a place name (`location`). CREDIT COST: 5 credits per call (chart 3 + render 2; +1 per place name). Human Design was originated by Ra Uru Hu; OpenEphemeris is an independent calculation service, not affiliated with Jovian Archive. - **explore_human_design_connection** β€” Use this when the user asks 'are we compatible in Human Design', 'what's our connection chart', 'what channels do we make together' or 'show our composite bodygraph' β€” two people's HD charts overlaid. Returns an interactive two-person overlay bodygraph (inline in Claude and ChatGPT; text summary elsewhere) with every connected channel classified by HD connection theory: electromagnetic (attraction), companionship (sameness), dominance (one defines), compromise (friction). CREDIT COST: 5 credits per call (composite 3 + render 2). Human Design was originated by Ra Uru Hu; OpenEphemeris is an independent calculation service, not affiliated with Jovian Archive. - **explore_bi_wheel** β€” Use this when the user asks 'are we compatible', 'compare my chart with my partner's', 'what's my horoscope for today', 'what's hitting my chart right now', 'what's my solar return chart this year' or 'my progressed chart on my birth chart' β€” any two-ring comparison they should SEE. Returns an interactive bi-wheel (inline in Claude and ChatGPT; text summary elsewhere): inner wheel Person 1's natal chart, outer ring by mode β€” synastry (Person 2's natal; needs their birthplace), transit (a date; today for a daily horoscope), progressed, solar_arc (target date), solar_return (target year), lunar_return (target month) β€” with cross-aspects drawn and every planet, aspect line and cusp clickable. Birthplaces may be place names (`location`, `person2_location`). CREDIT COST: 2 credits per call for most modes (1 per wheel; +1 to resolve a place name); solar_return/lunar_return modes cost 6. - **explore_moon_phase** β€” Use this when the user asks 'what's the moon phase tonight', 'is tonight a full moon', 'show me the moon right now', 'what sign is the Moon in', 'is the Moon void of course' β€” or has no birth data and wants somewhere to start; it needs no arguments. Returns an interactive Moon dial (inline in Claude and ChatGPT; text summary elsewhere) with: β€’ SVG crescent Moon showing real-time illumination percentage β€’ Phase name and waxing/waning indicator β€’ Current Moon sign with degree β€’ Void-of-Course status with timing details β€’ Lunar age (days in the synodic cycle) and days to the next New and Full Moon β€’ The tightest applying lunar aspects CREDIT COST: 3 credits per call (phase + void-of-course + aspects, 1 each). - **explore_transit_timeline** β€” Use this when the user asks 'what transits are coming up for me', 'what's my forecast for the next year', 'when will Saturn hit my chart', 'show my upcoming transits' or 'what's happening astrologically for me in 2027' β€” a forecast they should SEE. Returns an interactive, date-ordered timeline (inline in Claude and ChatGPT; text summary elsewhere) of exact transit hits grouped by month β€” transiting planet glyph, the natal point it contacts, the aspect, zodiac position and retrograde markers β€” each clickable for a focused interpretation. Every hit carries its in-orb window (when the transit starts and ends, and which pass it is when a retrograde repeats it), and transits already in orb at the start are listed with applying/separating. ASPECT ANGLES: 0 = conjunction/return (default), 180 = opposition, 90 = square, 120 = trine, 60 = sextile. EFFICIENCY: searches run faster when transiting_planets and natal_points are given. MAX SPAN: Explorer/PayG 1y, Pro 5y, Startup 10y, Scale 40y (longer = 400). CREDIT COST: 1 + span price: ≀1y 5 (6 total), ≀3y 10, ≀5y 15, ≀10y 25, ≀20y 40, ≀40y 70. - **explore_vedic_chart** β€” Use this when the user asks 'show my Vedic chart', 'my Jyotish chart', 'what's my nakshatra', 'my sidereal birth chart', 'my rashi chart' or 'what's my lagna'. Returns an interactive South Indian fixed-sign Rashi grid (inline in Claude and ChatGPT; text summary elsewhere) with sidereal (Lahiri by default) placements, nakshatra with pada, navamsa and the Lagna (Ascendant) rashi; click any rashi cell for its themes and the planets placed there. Birthplace may be a place name (`location`). CREDIT COST: 3 credits per call (chart + render; +1 to resolve a place name). - **bazi_annual_pillar** β€” Use this when the user asks 'what element is the year of the Snake', 'what's the pillar, stem and branch or NaYin for my birth year' or 'what's the energy of this year' β€” a single-year lookup beyond the animal. Returns the year's Heavenly Stem, Earthly Branch, Chinese characters, zodiac animal, element, polarity and NaYin (纳音) resonance image for any Gregorian year 1-9999. CREDIT COST: 3 credits per call. - **explore_bazi_chart** β€” Use this when the user asks 'what's my BaZi', 'my Four Pillars', 'what's my Day Master', 'my Chinese astrology chart', 'what's my Chinese element' or 'my Chinese birth chart'. Returns an interactive Four Pillars (ε››ζŸ±ε‘½η›˜) explorer (inline in Claude and ChatGPT; text summary elsewhere): the Year, Month, Day and Hour pillars β€” each with Heavenly Stem (倩干), Earthly Branch (εœ°ζ”―), Ten God label and element color β€” plus the Day Master identity and a Wu Xing (δΊ”θ‘Œ) element balance bar; click any pillar for what it reveals about that life domain. CREDIT COST: 3 credits per call (1 base + 2 visual render). - **auth_login** β€” Use this when the user asks to 'connect', 'sign in', 'log in' or 'link my OpenEphemeris account'. Returns a verification URL and code for the user to enter in their browser; the server then receives credentials automatically and every call is billed to that account (tier, credits, rate limits). - **auth_status** β€” Use this when the user asks 'am I logged in', 'which account is this connected to', 'how am I authenticated' or 'when does my token expire'. Returns whether the server is authenticated, the linked account, the method (API key, JWT, device auth) and token expiry. - **auth_logout** β€” Use this when the user asks to 'log out', 'sign out', 'disconnect' or 'switch accounts' on this MCP server. Returns confirmation that cached device-auth credentials were cleared; an API key set in the environment is not revoked. - **account_usage** β€” Use this when the user asks 'how many credits do I have left', 'what's my usage this month', 'am I close to my limit', 'what plan am I on' or 'how do I upgrade or top up'. Returns plan tier, billing period, credits used / included / remaining, percent of quota used, total API calls, and subscription status with renewal date; pass month='YYYY-MM' for a past period. CREDIT COST: 0. - **dev_read_api** β€” Use this when the user asks for something no typed tool covers β€” 'is today a good biodynamic planting day', 'what's the tidal forcing', 'what Chinese zodiac animal is 2026', 'which bodies do you support' β€” or any other allowlisted GET endpoint. Returns the endpoint's JSON. Read-only HTTP GET; POST endpoints are not accepted by this tool. Target API: Open Ephemeris REST API (https://api.openephemeris.com). Only allowlisted endpoint paths are accepted. CREDIT COST: 1 for most; /predictive/* 5 (transits/search 5-70 by span); /comparative/* 3; /calendar/* 10 (moon-phases, lunar-standstill 2; cross-quarter 5); /acg/* 10 (Pro); /electional/* 5 (span-priced searches are Pro tier; moment-analysis and station-tracker are not tier-gated); /human-design/*, /iching/* 2 (composite, transit-chart 3; penta 2/member); catalogs 0; 4xx/5xx refunded. Query {format: 'llm'} = compact output. COMMON CALLS: GET /ephemeris/moon/phase β€” Current/queried moon phase GET /ephemeris/moon/void-of-course β€” Next void-of-course period GET /ephemeris/agro/daily β€” Biodynamic farming day quality GET /ephemeris/agro/calendar β€” Multi-day biodynamic calendar GET /ephemeris/agro/void-of-course β€” Biodynamic VoC periods GET /eclipse/next-visible β€” Next eclipse visible from a location (query: lat, lon, type=solar|lunar) GET /eclipse/solar/global β€” Next global solar eclipse (query: date=YYYY-MM-DD) GET /eclipse/solar/local β€” Local solar eclipse (query: lat, lon) GET /tidal/forcing β€” Gravitational tidal forcing index GET /calendar/astrology/moon-phases β€” next New/Quarter/Full Moon after a date or jd GET /location/autocomplete β€” Geocode a place name (query: query=City Name) GET /chinese/zodiac β€” Chinese zodiac year element/animal GET /catalogs/bodies β€” List all supported celestial bodies - **dev_list_allowed** β€” Use this when the user asks 'what endpoints can you call', 'what else can this server do' or 'is /some/path available'. Returns every allowlisted API operation (method + path) grouped by method, plus the active deny rules; read locally, no API call. - **ephemeris_natal_chart** β€” Use this when the birth chart is wanted as data rather than a picture β€” 'give me my chart as JSON', 'list my natal aspects with orbs', 'what exact degree is my Ascendant', 'my placements as a table' β€” or as the input to a further calculation. Returns raw JSON: all major planets plus Chiron and the major asteroids (Ceres, Pallas, Juno, Vesta) β€” and, on request, any of ~90 more bodies via additional_objects (Eris, Sedna, Psyche, Hekate, Fortuna, Pandora, Asbolus and so on) β€” angles (ASC/MC/DSC/IC), house cusps, dignity condition, retrograde flags and the major aspect grid; format='llm' gives compact output. Takes coordinates, not a place name. CREDIT COST: 1 credit per call. - **ephemeris_transits** β€” Use this when the user asks 'when is my Saturn return', 'when does Pluto square my Sun', 'when will Jupiter conjunct my Moon', 'what transits do I have next year' β€” any WHEN-does-a-transit-hit question, as data. Returns the exact moments transiting planets form the requested aspect to natal points over a date range. ASPECT ANGLES (aspect_angle): 0 = conjunction/return (default), 180 = opposition, 90 = square, 120 = trine. Saturn return β†’ transiting_planets=['saturn'], natal_points=['saturn'], aspect_angle=0. EFFICIENCY: searches run faster when transiting_planets and natal_points are given; omitting both is slow. Default natal_points: sun, moon, mercury, venus, mars, jupiter, saturn. MAX SPAN: Explorer/PayG 1y, Pro 5y, Startup 10y, Scale 40y (longer = 400). CREDIT COST: 1 + span price: ≀1y 5, ≀3y 10, ≀5y 15, ≀10y 25, ≀20y 40, ≀40y 70. truncated:true = partial, with the resume point in truncation.resume_from. - **ephemeris_moon_phase** β€” Use this when the Moon's state is wanted as data for a specific moment β€” 'what phase was the Moon on my birthday', 'what sign was the Moon in on 12 May 1990', 'moon phase and illumination as numbers'. Returns phase name, illumination %, the Moon's sign and degree, and the next void-of-course window; omit datetime for right now. CREDIT COST: 2 credits β€” phase and void-of-course are metered separately (the phase-only endpoint /ephemeris/moon/phase costs 1). - **ephemeris_next_lunar_phase** β€” Use this when the user asks 'when is the next full moon', 'when is the next new moon', 'what date is the next quarter moon' or 'list the next 3 full moons'. Returns the exact UTC datetime of each upcoming occurrence of the requested phase (phase = new_moon | full_moon | first_quarter | last_quarter), optionally after a given date and for count occurrences. CREDIT COST: 2 credits per occurrence; count max 12. - **ephemeris_next_eclipse** β€” Use this when the user asks 'when is the next eclipse', 'when is the next solar / lunar eclipse', 'is there an eclipse visible from Tokyo' or 'when is the next total lunar eclipse'. Returns the eclipse type, date/time of maximum, magnitude and duration of totality; with latitude+longitude it adds local contact times and visibility for that place, without them it returns the next global eclipse of that type. CREDIT COST: 1 credit per call. - **human_design_chart** β€” Use this when the Human Design chart is wanted as data β€” 'give me my HD activations', 'which planets sit in which gates, design and personality', 'what are my variables', 'my Human Design chart as JSON'. Returns Type, Strategy, Authority, Profile, defined and undefined Centers, activated Gates and Channels, Incarnation Cross, and both Personality (birth) and Design (~88Β° of Sun before birth) planetary positions. CREDIT COST: 2 credits per call. HD is minute-sensitive: a zone-less datetime is rejected, because an hour of error changes the Profile and the Design Sun line. Takes coordinates, not a place name. - **ephemeris_synastry** β€” Use this when the relationship comparison is wanted as data β€” 'list our inter-aspects with orbs', 'what aspects does their Mars make to my Venus', 'our synastry as JSON'. Returns the cross-aspects between the two charts plus both natal charts; needs each person's birth datetime, zone and coordinates. CREDIT COST: 3 credits per call. - **ephemeris_relocation** β€” Use this when the user asks 'how does my chart change if I move to London', 'what's my relocated Ascendant in Tokyo' or 'recast my chart for where I live now'. Returns the natal chart re-cast for a new location β€” the same planetary longitudes with the houses and angles that place gives them. CREDIT COST: 1 credit per call. - **ephemeris_electional** β€” Use this when the user asks 'when is the best time to launch / sign / marry / start X' within a date range, 'find me a good day next month' or 'pick an auspicious window'. Returns the best continuous timing windows in the range, scored hourly on essential dignity, aspect quality, sect and void-of-course Moon penalties, with optional filters (avoid_voc, lunar_phase). CREDIT COST: ≀30 days 5, ≀60 days 8, ≀120 days 12. Pro tier; max window Pro 30 days, Startup 60, Scale 120. - **electional_moment_analysis** β€” Use this when the user asks 'is now a good time to …', 'what's the sky doing today', 'what's the astrological weather', 'how is this date astrologically' β€” or has no birth data (it works with no arguments). Returns planet positions, aspects, void-of-course status, lunar phase, day ruler, sect and an overall electional score (0-100) for one moment. CREDIT COST: 5 credits per call. - **electional_station_tracker** β€” Use this when the user asks 'when does Mercury go retrograde', 'when does Mercury retrograde end', 'when does Mars go direct', 'when does Pluto go direct', 'is Venus retrograde this year', 'Mercury retrograde dates for 2026' or 'what planets station this month'. Returns every retrograde and direct station in the range with exact time, longitude and sign β€” Mercury through Pluto; default range the next 90 days, maximum one year. CREDIT COST: 5 credits per call. - **vedic_chart** β€” Use this when the Vedic / Jyotish chart is wanted as data β€” 'my sidereal placements as JSON', 'nakshatra and pada for every planet as a table', 'my navamsa positions'. Takes coordinates, not a place name. Returns sidereal planet placements in rashis, nakshatras with pada, navamsa placements and bhavas (Whole Sign houses). SUPPORTED AYANAMSA: lahiri (default), fagan_bradley, krishnamurti, raman, yukteshwar CREDIT COST: 1 credit per call. - **ephemeris_solar_return** β€” Use this when the user asks 'when exactly is my solar return', 'my solar return positions as data' or 'my solar return for 2027 as JSON'. Returns the exact moment the Sun returns to its natal longitude near the birthday and the Solar Return chart for that year; target_datetime picks the year (defaults to the current one). CREDIT COST: 5 credits per call. - **ephemeris_progressed_chart** β€” Use this when the user asks 'what's my progressed chart', 'where is my progressed Moon / Sun', 'what sign has my progressed Moon moved into' or 'my solar arc directions'. Returns progressed planet positions, house cusps, aspects and retrograde status for a target date β€” method = secondary (1 day = 1 year, default), solar_arc or tertiary. CREDIT COST: 1 credit per call. - **ephemeris_planet_position** β€” Use this when the user asks 'where is Mars right now', 'what sign is Venus in today', 'what degree is the Sun at', 'where was Jupiter on my birthday', 'where is the North Node' β€” one body at one moment β€” or 'what's my star sign / zodiac sign' from a birth date alone (planet_id=0; a bare date resolves to noon UTC, no location needed). Returns ecliptic longitude, latitude, distance, speed and retrograde flag. PLANET IDS: 0=Sun, 1=Moon, 2=Mercury, 3=Venus, 4=Mars, 5=Jupiter, 6=Saturn, 7=Uranus, 8=Neptune, 9=Pluto, 10=North Node (Mean), 11=North Node (True), 12=Lilith (Mean), 15=Chiron, 17=Ceres, 18=Pallas, 19=Juno, 20=Vesta. NODES: id 10 is the mean North Node (mean-node polynomial); id 11 is the true North Node (osculating, referenced to the true ecliptic of date). There is no South Node id; the South Node longitude is a North Node longitude plus 180Β° (mod 360). CREDIT COST: 1 credit per call. - **ephemeris_house_cusps** β€” Use this when the user asks 'what are my house cusps', 'where does my 7th house start', 'show my houses in Whole Sign' or 'compare Placidus and Koch for my chart' β€” houses and angles only, for a date, time and place. Returns the twelve cusps and ASC/MC/DSC/IC for each requested system. HOUSE SYSTEM CODES: P=Placidus, K=Koch, O=Porphyry, R=Regiomontanus, C=Campanus, E=Equal, W=Whole Sign. CREDIT COST: 1 credit per call. - **ephemeris_retrograde_status** β€” Use this when the user asks 'is Mercury retrograde right now', 'is Venus retrograde today', 'was Mars retrograde when I was born' or 'which planets are retrograde at the moment'. Returns is_retrograde, longitude speed and station proximity for one planet at one instant (planet_id; Mercury is planet_id=2), or for all ten planets when planet_id is omitted. CREDIT COST: 1 credit for a single planet; omitting planet_id runs all ten planets (10 credits, one per body). - **ephemeris_angles_points** β€” Use this when the user asks 'where is my Vertex', 'what's my East Point / equatorial ascendant' or 'what are my chart angles' for a date, time and place. Returns ASC, MC, DSC, IC, Vertex and the Equatorial Ascendant/Descendant; the equatorial ascendant is also returned under `east_point` β€” a synonym for the same point, not a separate one. CREDIT COST: 1 credit per call. - **ephemeris_aspect_check** β€” Use this when the user asks 'is 15Β° Aries square 18Β° Cancer', 'what aspect is between these two positions', 'how many degrees apart are my Sun and Moon' or 'is this within orb'. Returns the angular separation between two ecliptic longitudes (longitude_1, longitude_2) and any aspect within orb (conjunction, sextile, square, trine, opposition, etc.). CREDIT COST: 1 credit per call. - **acg_power_lines** β€” Use this when the user asks 'show my astrocartography map', 'where are my Jupiter lines', 'where in the world is my Sun on the MC', or wants the whole-world list of their lines. Returns, per planet, its MC, IC, AC and DC lines (where it was culminating, anti-culminating, rising or setting at birth) with sign and equator-crossing longitude β€” geometry stripped, not for map rendering. CREDIT COST: 10 credits per call. Pro tier. - **acg_hits** β€” Use this when the user asks 'is Tokyo good for me', 'where should I live according to my chart', 'what planets affect me in Paris', 'which of my lines run through Lisbon' or 'should I move to Austin'. Returns every astrocartography line (power lines and aspect lines) within radius_deg of a query location, sorted by distance, for a given birth chart. CREDIT COST: 10 credits per call. Pro tier. - **location_search** β€” Use this when the user gives a birth city or any place name β€” 'born in Chicago', 'Portland', 'Mumbai, India' β€” and a chart needs coordinates and a timezone. Returns display name, region (state/province), latitude, longitude and IANA timezone. With the birth date as `date` it also returns `utcOffsetAtDate`, the historically-correct UTC offset for that place on that date; post-1970 dates resolve locally at no extra cost, pre-1970 dates consult the historical overlay for the top match (+1 credit) and return its provenance. The result is flagged `ambiguous` when several places share the name (e.g. "portland"). A trailing "City, ST" qualifier in the query is honored. CREDIT COST: 1 credit per call. - **timezone_resolve** β€” Use this when the user asks 'what timezone is this location in' or 'what was the UTC offset there on that date', or when latitude/longitude are known and the IANA timezone is needed to interpret a local birth time. Takes coordinates, not a place name. Returns the IANA zone and, with `date`, the historically-correct UTC offset that applied on that date. CREDIT COST: 1 credit per call. ## Claude Desktop Quick Installation Install path detected from listing signals. Uses `npx` (confidence: high): ```json "mcpServers": { "open-ephemeris": { "command": "npx", "args": ["-y","@openephemeris/mcp-server"], "env": { "OPENEPHEMERIS_PROFILE": "", "OPENEPHEMERIS_BACKEND_URL": "", "OPENEPHEMERIS_API_KEY": "" } } } ``` **Requires environment variables:** `OPENEPHEMERIS_PROFILE`, `OPENEPHEMERIS_BACKEND_URL`, `OPENEPHEMERIS_API_KEY` β€” the values above are empty placeholders; fill in real credentials before running (see the repository for what each one is for). ## Documentation ## What open-ephemeris does open-ephemeris exposes the Open Ephemeris REST API at `https://api.openephemeris.com` through Model Context Protocol. Its calculations use the NASA JPL DE440 ephemeris and cover approximately 1,100 years of astronomical data. The server is aimed at astrology and related esoteric workflows, including Western natal charts, transits, synastry, Human Design, Vedic astrology, Chinese BaZi, lunar phases, eclipses, electional timing, and astronomical lookups. Results can be returned as structured data or as interactive visualizations. Chart-oriented tools can render wheels, bodygraphs, timelines, dials, and grids inline in supported clients, while other clients receive text summaries. Place names can be resolved for several visual tools; lower-level data tools generally require latitude and longitude directly. ## How it works The MCP tools translate natural-language chart requests into calls to the Open Ephemeris API. Authentication can use an API key, browser-based device authentication, or the hosted service's OAuth flow. Account tools report the linked account, token state, plan, credit usage, and subscription information. The toolset separates visual exploration from data retrieval. For example, `explore_natal_chart` produces an interactive chart, while `ephemeris_natal_chart` returns placements, angles, houses, dignity, retrograde flags, and aspects as JSON. Similar pairs exist for Human Design, Vedic astrology, Moon data, transits, and other calculations. `dev_read_api` provides access to allowlisted read-only API paths, and `dev_list_allowed` lists those paths and their deny rules. ## Setup and configuration The hosted MCP endpoint is: ```text https://mcp.openephemeris.com/mcp ``` It uses Streamable HTTP and can be added as a custom connector in clients that support remote MCP. Claude Web can connect to the URL with OAuth handled through the browser. ChatGPT offers the service through its app directory. Smithery provides a managed connection option. For local stdio clients, install the npm package with `npx`: ```json { "mcpServers": { "openephemeris": { "command": "npx", "args": ["-y", "@openephemeris/mcp-server"], "env": { "OPENEPHEMERIS_PROFILE": "dev", "OPENEPHEMERIS_BACKEND_URL": "https://api.openephemeris.com", "OPENEPHEMERIS_API_KEY": "YOUR_API_KEY_HERE" } } } } ``` The same configuration can be used in Claude Desktop, Cursor, and Windsurf. The API key is obtained from the Open Ephemeris dashboard. Direct Streamable HTTP connections send it as the `X-API-Key` header. ## Tools and capabilities The server includes tools for: - Interactive Western natal charts, bi-wheels, transit timelines, Moon dials, solar returns, progressions, and relocation charts. - Raw natal, transit, Moon-phase, eclipse, synastry, solar-return, progressed-chart, and Human Design data. - Human Design charts, current transits, two-person connection overlays, and interpretations of centers, gates, channels, profiles, and authority. - Vedic charts with configurable ayanamsa options, nakshatras, padas, navamsa placements, and Whole Sign bhavas. - BaZi Four Pillars charts and annual pillar lookups with stems, branches, elements, polarity, zodiac animals, and NaYin. - Lunar phases, void-of-course periods, upcoming eclipses, planetary stations, tidal forcing, biodynamic calendars, supported-body catalogs, and allowlisted API reads. - Electional searches that score possible timing windows, plus single-moment astrological analysis. Credit costs vary by operation, rendering mode, and search span. Transit searches and other date-range calculations can cost more for longer ranges, and some capabilities are tier-gated. ## Limitations and notes Birth data must include an accurate local time and time zone where the calculation requires a clock time. Human Design is particularly minute-sensitive, and its data tool rejects zone-less datetimes. Some lower-level tools accept coordinates only, while visual tools may resolve a supplied place name. The server accepts only allowlisted GET operations through `dev_read_api`; POST endpoints are not supported by that tool. Transit searches have plan-dependent maximum spans, and electional searches have plan-dependent window limits. Solar-return and lunar-return visualizations have higher credit costs than most bi-wheel modes. Human Design was originated by Ra Uru Hu; Open Ephemeris describes itself as an independent calculation service and not affiliated with Jovian Archive. Logging out clears cached device-auth credentials but does not revoke an API key configured in the environment. _Full upstream README: https://allmcps.com/mcp/open-ephemeris/readme_