# GetBirthChart MCP [Health: Active]

**Category:** 🔮 Spirituality & Esoterica  
**Repository:** https://github.com/getbirthchart-com/getbirthchart-mcp  
**GitHub Stars:** 0  
**npm Downloads (last month):** 105  
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**Directory Page:** https://allmcps.com/mcp/getbirthchart-mcp

## Description
Official MCP server for GetBirthChart astrology calculations.

## Tools
Capabilities this server exposes over MCP:

- **calculate_birth_chart** — Omits Ascendant and houses; preserves uncertainty.
- **get_planet_positions** — Preserves chart uncertainty.
- **get_big_three** — Does not guess the Ascendant.
- **get_moon_sign** — Returns ambiguity when the backend cannot establish one sign.
- **get_rising_sign** — Returns `birth_time_required`.
- **calculate_aspects** — Returns backend-owned facts only.
- **calculate_synastry** — Preserves each person's unknown-time limits.

## Claude Desktop Quick Installation
Install path detected from listing signals. Uses `npx` (confidence: high):

```json
"mcpServers": {
  "getbirthchart-mcp": {
    "command": "npx",
    "args": ["-y","@getbirthchart/mcp@0.2.0"],
    "env": {
      "GETBIRTHCHART_API_KEY": "",
      "GETBIRTHCHART_API_BASE_URL": ""
    }
  }
}
```

**Requires environment variables:** `GETBIRTHCHART_API_KEY`, `GETBIRTHCHART_API_BASE_URL` — the values above are empty placeholders; fill in real credentials before running (see the repository for what each one is for).

## Documentation

## What GetBirthChart MCP MCP server does

GetBirthChart MCP MCP server connects MCP-compatible AI clients to the public GetBirthChart API for astrology calculations. The package does not implement or re-create the astrology engine; it forwards structured requests and exposes structured results as MCP tools. All tools are read-only.

The available operations cover natal charts, planetary placements, the Sun/Moon/Rising combination, Moon signs, Rising signs, natal aspects, and synastry between two people. Results preserve backend-owned facts and uncertainty. For example, an unknown birth time prevents the server from supplying houses or an Ascendant, and an uncertain Moon sign is returned as ambiguity rather than a forced selection.

## How it works

The server accepts birth data containing a date and, when known, a time. Latitude, longitude, and an IANA timezone are required; `place` can be included as a label but is not resolved into coordinates. Set `unknown_time` when the time is unavailable and omit the `time` field. The server does not replace missing times with noon or invent a Rising sign.

`get_rising_sign` requires an exact birth time and returns `birth_time_required` otherwise. Synastry retains the unknown-time restrictions for each person separately. Calculation failures use structured error data with a machine-readable code, message, retryability, and sometimes a retry delay.

Natal requests can expose options such as house system, node type, aspect preset, custom aspect rules, additional points, zodiac, and ayanamsa. Sidereal calculations require a named ayanamsa. Synastry also accepts relationship-level settings including node convention and optional relationship metadata. The MCP contract exposes calculations, not interpretation; composite and Davison operations are not tools in this release.

## Setup and configuration

Run GetBirthChart MCP MCP server with Node.js 20 or newer and a GetBirthChart developer API key. The package can be launched with `npx` using the `@getbirthchart/mcp@0.2.0` package and an MCP host's command-based server configuration.

Set `GETBIRTHCHART_API_KEY` in the host environment. The key is read at startup, is not accepted as a tool argument, and is not written to protocol output, logs, resources, or tool results. `GETBIRTHCHART_API_BASE_URL` is optional for development or testing. HTTPS is required except for localhost HTTP use; do not send a production key to an untrusted endpoint.

The package does not persist, cache, or log birth inputs and has no analytics or telemetry. It also provides three resources: methodology, data-source provenance, and engine information.

## Tools and capabilities

- `calculate_birth_chart` returns a mapped natal chart and omits houses and the Ascendant when the time is unknown.
- `get_planet_positions` returns planetary placements while retaining chart uncertainty.
- `get_big_three` returns the Sun, Moon, and an optional Rising sign without guessing.
- `get_moon_sign` reports the Moon sign or ambiguity when one sign cannot be established.
- `get_rising_sign` returns the Rising sign only when an exact time is available.
- `calculate_aspects` returns natal aspects based on backend-owned facts.
- `calculate_synastry` compares two people while preserving each person's time-related limits.

GetBirthChart MCP MCP server is suited to agents that need machine-readable calculation data rather than prose interpretations. Common API errors include validation, authentication, location, rate-limit, timeout, and internal failures.

_Full upstream README: https://allmcps.com/mcp/getbirthchart-mcp/readme_