Astrology MCP server

Server URL: https://www.natalchart.ai/mcp. It speaks the Model Context Protocol over streamable HTTP, so any client that supports remote MCP servers can use it. Ask your assistant for a birth chart, a compatibility reading or the best city to move to, and it calls the tools below for the numbers first.

Connect in two minutes

1. Create a free API key. It starts with nc_live_ and is shown once.
2. Add the server to your assistant, as shown below for each client.
3. Ask about a chart: “I was born on 6 September 1991 at 10:45 in Chornomorsk, Ukraine. What is my rising sign, and what does my 10th house say about work?”

Claude (claude.ai and Claude Desktop)

Open Settings, then Connectors, add a custom connector and paste this URL with your key in place of YOUR_KEY:

https://www.natalchart.ai/mcp?key=YOUR_KEY

ChatGPT

With developer mode turned on in ChatGPT’s settings, create a connector with the same URL and no authentication. The key travels inside the URL.

Claude Code

claude mcp add --transport http natalchart https://www.natalchart.ai/mcp \
  --header "Authorization: Bearer YOUR_KEY"

Cursor

In ~/.cursor/mcp.json:

{
  "mcpServers": {
    "natalchart": {
      "url": "https://www.natalchart.ai/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_KEY"
      }
    }
  }
}

VS Code

In .vscode/mcp.json; VS Code asks for the key once and keeps it out of the file:

{
  "inputs": [
    {
      "type": "promptString",
      "id": "natalchart-key",
      "description": "NatalChart.AI API key",
      "password": true
    }
  ],
  "servers": {
    "natalchart": {
      "type": "http",
      "url": "https://www.natalchart.ai/mcp",
      "headers": {
        "Authorization": "Bearer ${input:natalchart-key}"
      }
    }
  }
}

Tools

Birth data is the same everywhere: date as YYYY-MM-DD, time as local HH:mm or null when unknown, latitude and longitude, and an optional IANA timezone. Assistants look up the coordinates of a birth place themselves. With an unknown time, everything that depends on it (the Ascendant, the houses) is withheld rather than guessed.

Limits and price

The MCP server is part of the NatalChart.AI API: one key, one daily pool, one subscription. A call that fails validation costs nothing, a Pro tool called on a free key answers with how to get it, and usage is always free.

Why a calculation server

Language models are good at explaining a chart and bad at computing one: asked for a Moon sign or an Ascendant from memory, they often get it wrong, and nothing in the answer shows it. With this server the positions come from the Swiss Ephemeris, the same engine the NatalChart.AI chart calculator uses and that the accuracy report checks against NASA’s JPL Horizons. The model then does what it is good at.

Questions