API & MCP

Everything a person can do on Skyfold Sun Position and Shadow Length, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://skyfoldsunshadow.usefulweb.app/api/v1/calculate – run Skyfold Sun Position and Shadow Length
GET https://skyfoldsunshadow.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 Sun Position and Shadow Length

Computes the Sun’s azimuth and altitude, the length and compass direction of the shadow cast by an object of a given height on level ground, the shadow through the day, sunrise, solar noon, sunset and golden hour, plus a day-and-night map.

Inputs of Skyfold Sun Position and Shadow Length
Field	Type	Default	Description
`location`	text	"48.1351, 11.582"	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/Berlin"	Time zone. IANA name such as Europe/Berlin or America/New_York, or a fixed offset such as UTC+2.
`date`	date	"2026-03-20"	Local date
`time`	time	"16:00"	Local time
`height`	number	6	Object height
`unit`	select (m, ft)	"m"	Unit
`stepMinutes`	select (15, 30, 60)	"60"	Table step

Example request

A 6 m tree in Munich at the March equinox

curl -X POST https://skyfoldsunshadow.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"location":"48.1351, 11.582","elevation":520,"timeZone":"Europe/Berlin","date":"2026-03-20","time":"16:00","height":6,"unit":"m","stepMinutes":"60"}'

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://skyfoldsunshadow.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: skyfold_sun_shadow
Local stdio connector: node src/mcp-stdio.ts --tool=skyfold-sun-shadow

{
  "mcpServers": {
    "skyfold-sun-shadow": { "type": "http", "url": "https://skyfoldsunshadow.usefulweb.app/mcp" }
  }
}