openephemeris-api-reference

openephemeris-api-reference is a skill for Claude Code, Codex from openephemeris/openephemeris-MCP. It costs 57 tokens per session (3,111 once invoked), scanned A, original, MIT.

A reference guide to the OpenEphemeris API, a service for astronomical and astrological calculations. It lists the exact paths, inputs, and procedures for 120 API endpoints.

In plain words
What is it for?
Use it to find endpoints for birth charts, astrocartography, and other supported astronomical or astrological calculations.
Why use it?
It removes the need to guess endpoint names, parameters, or required birth-location data when using the API.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to find endpoints for birth charts, astrocartography, and other supported astronomical or astrological calculations.

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Install with agentmods
npx agentmods add skills/openephemeris/openephemeris-mcp/openephemeris-api-reference
Install

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.

Any agent
npx skills add openephemeris/openephemeris-MCP --skill openephemeris-api-reference
Clone the repo
git clone --depth 1 https://github.com/openephemeris/openephemeris-MCP

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for openephemeris-api-reference

README.md
[![agentmods](https://agentmods.dev/badge/skills/openephemeris/openephemeris-mcp/openephemeris-api-reference/github.svg)](https://agentmods.dev/skills/openephemeris/openephemeris-mcp/openephemeris-api-reference)
Your own site
<a href="https://agentmods.dev/skills/openephemeris/openephemeris-mcp/openephemeris-api-reference"><img src="https://agentmods.dev/badge/skills/openephemeris/openephemeris-mcp/openephemeris-api-reference/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.

agentmods 80×15 button for openephemeris-api-reference

Your own site · 80×15
<a href="https://agentmods.dev/skills/openephemeris/openephemeris-mcp/openephemeris-api-reference"><img src="https://agentmods.dev/badge/skills/openephemeris/openephemeris-mcp/openephemeris-api-reference.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,111 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00057 $0.03111
Opus 5 $0.00028 $0.01555
Sonnet 5 $0.00011 $0.00622
Haiku 4.5 $0.00006 $0.00311

Measured 12d ago against content hash 3444fc5e6762, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

openephemeris-api-reference 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 12d ago.

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.

skills/openephemeris-api-reference/SKILL.md · 263 lines

How it starts

The opening of the file, as written. The whole thing — 263 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OpenEphemeris API Reference

Quick reference for all 120 endpoints across 19 groups. Every endpoint works via:

  • MCP dev_read_api / dev_write_api with method + path (for allowlisted endpoints — see dev_list_allowed)
  • Direct REST to https://api.openephemeris.com with header X-Meridian-API-Key: oe_...

Always pass format=llm (query param or body field) unless raw JSON is requested — reduces tokens ~73%.

Standard Procedure Reminder

For ANY chart endpoint that takes birth data:

  1. GET /location/autocomplete?query=<city> → lat/lon
  2. POST /timezone/lookup with {latitude, longitude} → IANA timezone string
  3. Build birth_location with latitude, longitude, AND timezone — all three required
  4. Build birth_datetime with iso field as local civil time (the engine handles UTC conversion)
  5. Call the chart endpoint

ACG / Astrocartography (16)

Method Path Tier Description
POST /acg/power-lines Dev Planet AC/MC/DC/IC lines globally
POST /acg/hits Dev Lines near a target city
POST /acg/crossings Scale Where two lines intersect
POST /acg/parans Dev Latitude bands where two planets are simultaneously angular
POST /acg/midpoints Scale Planetary midpoint lines
POST /acg/declination-lines Scale Parallels of declination
POST /acg/aspects Scale Where natal planets aspect local angles
POST /acg/local-space Dev Azimuthal directions from a reference city
POST /acg/hermetic-lines Dev Hermetic Lots projected as lines
POST /acg/relational-parans Scale Parans for two-person synastry
POST /acg/ccg Scale Cyclocartography time-series
POST /acg/ccg/parans Scale Transit parans
POST /acg/heatmap/composite Service Composite heatmap
POST /acg/features Service Combined ACG feature collection
GET /acg/datasets Free Available ACG datasets
GET /acg/meta Free ACG engine metadata

Read the full file on GitHub · 263 lines

Changes

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.

  1. 12d ago First seen · 263 lines · 57 tokens per session scan A 3444fc5e6762

Subscribe to this mod's changes

openephemeris-api-reference is a skill published in the GitHub repository openephemeris/openephemeris-MCP (4 stars, last pushed yesterday), licensed MIT. It adds 57 tokens to every session and 3,111 once invoked, about $0.0003 per session on Opus 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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