For AI agents · MCP server
Give your assistant a living sky to query.
Your assistant already knows how to hold a conversation. Now it can look up. Ask about tonight's sky, someone's chart, the next eclipse — and it quietly reaches for the real numbers instead of making them up.
- things it can look up
- 91 tools
- things it can look up
- answers from real data
- No guessing
- answers from real data
- to connect it
- One click
- to connect it
Draw my birth chart — March 21 1990, noon, London.
ephemeris_chart_wheel1.2sActual API output — not a mock-up
Connect it now
One connector, about thirty seconds. Signing in creates your free account — nothing to install.
Connect Claude in ~30 seconds
A remote MCP connector — no download, no API key. OAuth handles sign-in and creates your account on first connect.
- 1Click "Add to Claude" above — it copies the URL and opens Claude → Settings → Connectors.
- 2Click "Add custom connector", then paste the URL into the URL field (Ctrl/⌘+V).
- 3Leave the OAuth Client ID and Secret blank and click "Add". Approve the sign-in popup — that also creates your free OpenEphemeris account.
Custom connectors require a paid Claude plan (Pro or higher). On the Claude desktop app and Claude Code, all plans work.
Using Claude Desktop, Cursor, or another client? See all setup options →
On Claude's free plan? Use the Claude Desktop config below — every plan works there.
Your birth data never trains a model — we don't sell it, share it, or feed it to anyone. Privacy policy
Say it plainly. It handles the rest.
You ask in your own words. Claude picks the right tool, sends the right parameters, and answers from computed data.
“What's in the sky right now?”
A live snapshot of every planet, tonight.
current_sky_snapshot“Draw my birth chart.”
An interactive wheel you can click and explore.
explore_natal_chart“Are we actually compatible?”
Two charts, honestly compared.
ephemeris_synastry“Where on Earth am I luckiest?”
Your planetary lines drawn across the map.
acg_power_lines“Any big transits hitting me this month?”
Exact dates, not vague vibes.
ephemeris_natal_transits“What's my Human Design type?”
An interactive bodygraph — type, strategy, authority.
explore_human_design“When is the next eclipse?”
Down to the minute, anywhere on Earth.
ephemeris_next_eclipse“Read my Chinese four pillars.”
BaZi chart with Ten Gods and luck pillars.
chinese_baziFree to start. Pennies to keep going.
Every account starts with 150 free credits — about 150 natal charts, no card. Richer questions cost more credits (synastry 3, maps 10). When they run low, top up your wallet for a few dollars. No subscription, no monthly bill. Credits never expire.
Pay only for what you use
Not using Claude.ai?
All 91 tools work in Claude Desktop, Claude Code, Cursor, Windsurf, ChatGPT, and any MCP-compatible client.
{
"mcpServers": {
"openephemeris": {
"command": "npx",
"args": ["-y", "@openephemeris/mcp-server"]
}
}
}Settings → Developer → Edit Config. Paste, save, restart. No API key required — first tool call prompts you to link your account.
Self-hosted and CLI clients authenticate with an API key from your dashboard. Free Explorer tier — 150 credits to start (one-time), no card required.
Your client will list about 32 tools, not 91
That's on purpose. A long tool list eats context and makes assistants pick badly, so a fresh connection advertises a focused everyday set — one interactive app per tradition, the main data tool per domain, and geocoding. Nothing is removed: all 91 tools stay callable by name, and dev_list_allowed lists what else is reachable.
Want everything advertised up front? Ask for the full catalog:
- Local (npx):
OPENEPHEMERIS_TOOLS=fullin the server'senvblock - Hosted URL:
https://mcp.openephemeris.com/mcp?profile=full
The surface is fixed when the session starts — reconnect after changing it.
Frequently Asked Questions
What is an astrology MCP server?+
An MCP (Model Context Protocol) server is a connector that gives AI assistants callable tools. The OpenEphemeris MCP server carries 91 astrology tools — natal charts, transits, synastry, astrocartography, Human Design, and BaZi — so your assistant answers from real computed data backed by NASA JPL DE440 instead of guessing.
How do I connect Claude to real astrology data?+
On claude.ai, add the OpenEphemeris connector in one click — signing in creates your free account, nothing to install. On Claude Desktop, paste a short JSON config; in Claude Code, run one terminal command. Your first tool call prompts you to link your account — no API key needed to start.
Does it work with ChatGPT, Cursor, and other MCP clients?+
Yes. All 91 tools work in Claude Desktop, Claude Code, Cursor, Windsurf, ChatGPT, and any MCP-compatible client. Clients that accept a hosted MCP URL connect to mcp.openephemeris.com/mcp with an API key in the X-API-Key header.
Why does my client only list about 32 tools?+
That is the default tool surface, and it is deliberate. A connection advertises about 32 everyday tools — one interactive app per tradition, the main data tool per domain, geocoding — because a shorter list makes the assistant pick better. Nothing is removed: all 91 tools stay callable by name, and dev_list_allowed enumerates the rest. To advertise the whole catalog, run the package with OPENEPHEMERIS_TOOLS=full, or add ?profile=full to the hosted URL.
Is there a free trial?+
Yes. Every account starts with 150 free trial credits — about 150 natal charts — no credit card required. Credits never expire, and you can top up your wallet from $5 when they run low.