Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add openephemeris/openephemeris-MCP --skill openephemeris-setupgit clone --depth 1 https://github.com/openephemeris/openephemeris-MCPWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/openephemeris/openephemeris-mcp/openephemeris-setup)<a href="https://agentmods.dev/skills/openephemeris/openephemeris-mcp/openephemeris-setup"><img src="https://agentmods.dev/badge/skills/openephemeris/openephemeris-mcp/openephemeris-setup/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/openephemeris/openephemeris-mcp/openephemeris-setup"><img src="https://agentmods.dev/badge/skills/openephemeris/openephemeris-mcp/openephemeris-setup.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00056 | $0.01361 |
| Opus 5.5 | $0.00022 | $0.00544 |
| Sonnet 5.5 | $0.00011 | $0.00272 |
| Haiku 4.5 | $0.00006 | $0.00136 |
Grade A, and why
openephemeris-setup scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 113 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Open Ephemeris Setup
This skill installs the Open Ephemeris MCP server, giving any compatible LLM access to 110+ astronomical and astrological computation endpoints — natal charts, transits, returns, eclipses, synastry, Human Design, Vedic, Chinese astrology, and astrocartography.
Platform compatibility: The MCP server works with Claude (Desktop, Code, API), ChatGPT (one-click install from the ChatGPT app directory), Cursor, Windsurf, VS Code Copilot, Cline, Continue.dev, JetBrains AI, and Amazon Q. Claude and ChatGPT additionally render the interactive charts inline — the same build, no per-host variant. For ChatGPT Custom GPTs and other non-MCP platforms, use the REST API directly at
api.openephemeris.comwith the OpenAPI spec.
Install
npx -y @openephemeris/mcp-server
Or add it permanently to your MCP configuration (Claude Code shown):
claude mcp add openephemeris -- npx -y @openephemeris/mcp-server
Get an API Key
- Sign up at https://openephemeris.com/login?signup=true (free, no credit card)
- Go to Dashboard → Account → Create API Key
- Copy the key (starts with
opene-) - Set the environment variable:
# macOS / Linux
export OPENEPHEMERIS_API_KEY="opene-..."
# Windows PowerShell
$env:OPENEPHEMERIS_API_KEY = "opene-..."
Verify
Ask Claude to use the ephemeris_moon_phase tool with datetime set to right now. If it returns moon phase data, setup is complete.
What You Get
Typed Tools
| Tool | Purpose |
|---|---|
ephemeris_natal_chart |
Full natal chart |
ephemeris_transits |
Search transit events over a date range |
ephemeris_ingresses |
When a planet changes sign or reaches a degree |
ephemeris_moon_phase |
Moon phase, sign, illumination |
ephemeris_next_eclipse |
Next eclipse visible from a location |
ephemeris_synastry |
Two-person compatibility |
ephemeris_relocation |
Relocate a chart to another city |
ephemeris_electional |
Find optimal timing windows |
human_design_chart |
Bodygraph (type, strategy, authority, profile, gates, channels) |
human_design_transit_timeline |
Gates transits enter and leave over a date range |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday Changed f0b981de5adf
- 2d ago Changed · +2 lines 7f9232e9317b
- 8d ago Changed f0b6f95c105b
- 28d ago Changed ca2b1efe32f0
- 1mo ago Changed c4fbeb2abe9c
- 1mo ago Changed 25670a53c0ab
- 1mo ago Changed e894420a3853
- 1mo ago Changed 980a90137058
- 1mo ago Changed 805020b174e0
- 1mo ago First seen · 111 lines · 56 tokens per session scan A b924944c5a95
openephemeris-setup is a skill published in the GitHub repository openephemeris/openephemeris-MCP (5 stars, last pushed yesterday), licensed MIT. It adds 56 tokens to every session and 1,361 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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