API & MCP

Everything a person can do on Skyfold Planet and Moon Positions, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://skyfoldplanetpositions.usefulweb.app/api/v1/calculate – run Skyfold Planet and Moon Positions
GET https://skyfoldplanetpositions.usefulweb.app/api/v1/tool – inputs, output schema, examples
OpenAPI 3.1: /openapi.json · /openapi.yaml
Errors: application/problem+json; 422 includes per-field errors.

Skyfold Planet and Moon Positions

Apparent right ascension, declination, azimuth, altitude, distance, magnitude and phase of the Sun, Moon and seven planets for a place and local time, with rise, transit and set times, twilight and the next Moon phases.

Inputs of Skyfold Planet and Moon Positions
Field	Type	Default	Description
`location`	text	"52.0907, 5.1214"	Location (latitude, longitude). Decimal degrees such as 52.09, 5.12 (north and east positive), or DMS, UTM, MGRS, Maidenhead or a plus code.
`elevation`	number	0	Elevation above sea level
`timeZone`	text	"Europe/Amsterdam"	Time zone. IANA name such as Europe/Berlin or America/New_York, or a fixed offset such as UTC+2.
`date`	date	"2026-11-07"	Local date
`time`	time	"22:00"	Local time

Example request

Utrecht on a November evening

curl -X POST https://skyfoldplanetpositions.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"location":"52.0907, 5.1214","elevation":5,"timeZone":"Europe/Amsterdam","date":"2026-11-07","time":"22:00"}'

Every result contains

inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.

MCP (Model Context Protocol)

Streamable HTTP endpoint: https://skyfoldplanetpositions.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: skyfold_planet_positions
Local stdio connector: node src/mcp-stdio.ts --tool=skyfold-planet-positions

{
  "mcpServers": {
    "skyfold-planet-positions": { "type": "http", "url": "https://skyfoldplanetpositions.usefulweb.app/mcp" }
  }
}