# Naelos.ai MCP server

Accurate astrology calculations for AI assistants, free and with no account. Connect it and your assistant calculates charts, transits and timing from NASA JPL data instead of estimating them.

- Server address: `https://mcp.naelos.ai/mcp`
- Transport: Streamable HTTP (MCP 2025-06-18), stateless
- Cost: free. No account, no key.
- Engine: Naelos Ephemeris, from NASA JPL DE440/DE441, 13,200 BC – AD 17,191 (https://naelos.ai/ephemeris.md)

## Tools

All tools are read-only. Places are given as latitude, longitude and an IANA time zone (for example `America/New_York`); assistants supply these for any named city.

| Tool | What it answers |
|---|---|
| `natal_chart` | A birth chart: every planet's sign, degree and house, the Ascendant and Midheaven, retrogrades, and aspects with exact orbs. Nine house systems. |
| `sky_now` | Where every planet is at a moment (now by default), with aspects; houses and angles when a place is given. |
| `planet_position` | One body's position on any date from 13,200 BC to AD 17,191, with its speed and whether it is retrograde. |
| `transits` | Every exact transit of the Sun through Pluto to a birth chart's planets and angles over a span of up to a year, each with its date. |
| `synastry` | The aspects between two people's charts, tightest first. |
| `returns` | A solar return for a year, or the lunar return nearest now, for the birthplace or another location. |
| `progressions` | Secondary progressions or solar arc directions as of today. |
| `timing_events` | Sign ingresses, new and full Moons and quarters, and retrograde and direct stations between two dates (up to two years). |
| `eclipses` | Solar and lunar eclipses between two dates (up to twenty years), with type, moment and degree. |
| `naelos_library` | Which of Naelos's 198 national charts and 19 empire charts exist, with the founding each is cast for. The charts themselves are in the Naelos app. |

Every answer gives the results in plain English and as JSON, names Naelos Ephemeris as the source, and links to naelos.ai, where the full chart wheel, readings and timing tools are.

## Connect it

**Claude (claude.ai and Claude Desktop).** Settings → Connectors → Add custom connector. Name it Naelos.ai and give the address `https://mcp.naelos.ai/mcp`.

**Claude Code.**

```
claude mcp add --transport http naelos https://mcp.naelos.ai/mcp
```

**ChatGPT.** Where your plan offers custom connectors (developer mode, under Settings → Apps & Connectors), add a connector with the address `https://mcp.naelos.ai/mcp` and no authentication.

**Cursor.** In `~/.cursor/mcp.json`:

```json
{ "mcpServers": { "naelos": { "url": "https://mcp.naelos.ai/mcp" } } }
```

**VS Code.** In `.vscode/mcp.json`:

```json
{ "servers": { "naelos": { "type": "http", "url": "https://mcp.naelos.ai/mcp" } } }
```

Any other client that speaks MCP over Streamable HTTP connects the same way, with the address above.

## Limits

Each client may make 30 calls a minute and 600 a day. Beyond that the server answers 429 until the window passes.

## Privacy

Nothing a caller sends is stored. Birth data is used for the calculation and discarded. The server logs only which tool was called, how long it took and whether it worked. See https://naelos.ai/privacy.

## Accuracy, and what it is not

Positions match NASA JPL to within 0.02″ across 1550–2649 and are checked against JPL Horizons from 9000 BC to AD 9000 (https://naelos.ai/ephemeris.md). The tropical zodiac is used. If a birth time is unknown, noon is used and the answer says houses and angles are unreliable.

The tools calculate; they do not interpret. Astrological readings are for reflection and entertainment, not for decisions about health, money or law.