CycleCalcs Astronomy MCP MCP server

An official MCP server providing eleven read-only astronomy tools backed by the CycleCalcs API. It allows AI agents to retrieve real-time data on celestial bodies, including sun and moon positions, eclipse events, twilight times, and planetary alignments, using a stateless Streamable HTTP endpoint.

Endpoint and access

No sign-in: your client connects and lists tools immediately, with no account or key.

No sign-inEndpoint checked 2026-10-05Operated by CycleCalcs

MCP endpoint (Streamable HTTP)

https://www.cyclecalcs.com/mcp

Vendor documentation

What you can do with it

Retrieve current sky conditions and moon phases for a specific location
Calculate sunrise, sunset, and twilight times for a given date
Identify upcoming solar and lunar eclipses with local visibility details
Get exact positions and brightness of planets for observational planning

Tools advertised by the last live check:

astro_sky_today
astro_sun
astro_moon
astro_moon_phases
astro_positions
astro_rise_set
astro_eclipses
astro_dark_window
astro_planet_board
astro_planet_events
astro_find_place

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers a Streamable HTTP server. Use --scope project to write .mcp.json for the repo.

Claude Code configuration

claude mcp add --transport http cyclecalcs-astronomy-mcp https://www.cyclecalcs.com/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).

Codex configuration

codex mcp add cyclecalcs-astronomy-mcp --url https://www.cyclecalcs.com/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable cyclecalcs-astronomy-mcp in your MCP settings.

Cursor configuration

{
  "mcpServers": {
    "cyclecalcs-astronomy-mcp": {
      "url": "https://www.cyclecalcs.com/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure). The type must be streamableHttp for a remote HTTP server.

Cline configuration

{
  "mcpServers": {
    "cyclecalcs-astronomy-mcp": {
      "type": "streamableHttp",
      "url": "https://www.cyclecalcs.com/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start cyclecalcs-astronomy-mcp and inspect its tools.

VS Code configuration

{
  "servers": {
    "cyclecalcs-astronomy-mcp": {
      "type": "http",
      "url": "https://www.cyclecalcs.com/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.

Gemini CLI configuration

gemini mcp add --transport http cyclecalcs-astronomy-mcp https://www.cyclecalcs.com/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.

Claude Desktop configuration

{
  "mcpServers": {
    "cyclecalcs-astronomy-mcp": {
      "url": "https://www.cyclecalcs.com/mcp"
    }
  }
}

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.

Windsurf configuration

{
  "mcpServers": {
    "cyclecalcs-astronomy-mcp": {
      "serverUrl": "https://www.cyclecalcs.com/mcp"
    }
  }
}

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