Open Ephemeris MCP Server

Model Context Protocol server for OpenEphemeris - typed astrology tools powered by the NASA JPL DE440 ephemeris. Zero hallucination on planetary positions, dates, and degrees. Covers 1,100 years of astronomical data. Its 27 documented tools cover ephemeris, chart, human, design. It is available as a remote MCP endpoint.

Teams that want a hosted design endpoint instead of running a local process. The project is written in Python.

VERIFIED ACTIVE

LAST COMMIT 2026-08-23 · ★ 3 · #67 OF 74 MAINTAINED DESIGN · VERIFIED 2026-08-25

MIT · Python servers · how we verify → /methodology

01 · Install Open Ephemeris

before you install - you'll need

Set OPENEPHEMERIS_API_KEY, OPENEPHEMERIS_TELEMETRY, DO_NOT_TRACK before connecting. OPENEPHEMERIS_PROFILE, OPENEPHEMERIS_BACKEND_URL, OPENEPHEMERIS_TOOLS are optional or environment-specific per the README.

Claude Code

claude mcp add openephemeris-openephemeris-mcp --transport http https://mcp.openephemeris.com/mcp

Claude Desktop / Cursor / VS Code - add to config

{
  "mcpServers": {
    "openephemeris-openephemeris-mcp": {
      "url": "https://mcp.openephemeris.com/mcp"
    }
  }
}

Same JSON for Cursor. For VS Code, rename the top-level key from `mcpServers` to `servers`.

Using another client? Same JSON, different key

Claude Desktop · mcpServers

Cursor · mcpServers

VS Code · servers

Windsurf · mcpServers

Zed · context_servers

Cline · mcpServers

Roo Code · mcpServers

Continue · mcpServers

LibreChat · mcpServers

Gemini CLI · mcpServers

Codex CLI · mcp_servers

Full setup guides: every client.

02 · Evidence

https://mcp.openephemeris.com/mcp

transport: streamable-http

endpoint alive - authentication required · probed 2026-08-25

Security posture

What to check before giving this server access to your agent - from the registry, GitHub, and our own probes. We don't score safety; we show what's verifiable.

runs as remote - your agent's requests go to mcp.openephemeris.com

endpoint auth requires authentication - rejected our unauthenticated MCP initialize

license MIT - declared in the repository

registry vendor namespace com.openephemeris - domain-verified with the official MCP registry

03 · What Open Ephemeris can do

Prose above is summarized from the project's README and registry record - no invented capabilities.

What you can build

An agent gets 27 documented tools spanning ephemeris, chart, human, design, including ephemeris_natal_chart, ephemeris_transits, ephemeris_natal_transits, ephemeris_moon_phase.

Capability map

Tools grouped from the project's README - what Open Ephemeris lets an agent do.

Ephemeris

15 tools - e.g. Explorer; Explorer; Explorer

ephemeris_natal_chart · ephemeris_transits · ephemeris_natal_transits · ephemeris_moon_phase · ephemeris_next_eclipse · ephemeris_electional…

Human

5 tools - e.g. Explorer; Developer; Developer

human_design_chart · human_design_composite · explore_human_design_transit · explore_human_design_connection · human_design_penta

Electional

3 tools - e.g. Developer; Developer; Developer

electional_moment_analysis · electional_station_tracker · electional_aspect_search

Acg

2 tools - e.g. Developer; Scale

acg_power_lines · acg_hits

Vedic

1 tool - e.g. Explorer

vedic_chart

Chinese

1 tool - e.g. Explorer

chinese_bazi

Latest releases

v4.12.0 · 2026-08-23

Connector first-run activation instrumentation, zero-argument tool instruction fix, and corrected endpoint counts in skills. Published to npm as 4.12.0 (current latest).

v4.11.2 · 2026-08-23

location_search accepts country names; includes 4.11.0 plugin-manifest sync and 4.11.1 fixes. Published to npm as 4.11.2.

v4.10.0 · 2026-08-23

BaZi tools now forward the timezone argument and accept convention parameters. Published to npm as @openephemeris/mcp-server 4.10.0.

04 · Who maintains Open Ephemeris

open-ephemeris is maintained by openephemeris. It's the only MCP server we track from this author; the repo dates to Mar 2026.

05 · Facts

repository: github.com/openephemeris/openephemeris-mcp
website: https://openephemeris.com/
category: design - ranked #67 of 74 actively-maintained design servers as of 2026-08-25.
release cadence: 4 releases in the last 90 days (latest 2026-08-23)
registry: com.openephemeris/open-ephemeris (active, first published 2026-08-23)

06 · Open Ephemeris FAQ

Is Open Ephemeris still maintained?

Yes - as of 2026-08-25, its last commit was 2026-08-23 and it shipped 4 releases in the last 90 days. We re-verify nightly.

What can Open Ephemeris do?

An agent gets 27 documented tools spanning ephemeris, chart, human, design, including ephemeris_natal_chart, ephemeris_transits, ephemeris_natal_transits, ephemeris_moon_phase.

How do I install Open Ephemeris?

Run `claude mcp add openephemeris-openephemeris-mc --transport http https://mcp.openephemeris.com/mcp`. The README documents 6 environment variables (OPENEPHEMERIS_PROFILE, OPENEPHEMERIS_BACKEND_URL, OPENEPHEMERIS_API_KEY…) to set first. Set OPENEPHEMERIS_API_KEY, OPENEPHEMERIS_TELEMETRY, DO_NOT_TRACK before connecting. OPENEPHEMERIS_PROFILE, OPENEPHEMERIS_BACKEND_URL, OPENEPHEMERIS_TOOLS are optional or environment-specific per the README. You can also paste the ready-made client config above.

Does Open Ephemeris require authentication?

Yes - when we probed the endpoint on 2026-08-25, it rejected an unauthenticated MCP initialize; you'll need credentials to connect.

07 · Alternatives to Open Ephemeris

Alternatives to Open Ephemeris

Maintained design servers if Open Ephemeris isn't the fit.

More design MCP servers · Amazon MCP · Figma MCP Server (planetabhi) · Pudge UI · HIG Doctor

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