API & MCP

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

HTTP API

POST https://hearthsunwindows.usefulweb.app/api/v1/calculate – run Sun Windows
GET https://hearthsunwindows.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.

Sun Windows

Explore direct-sun windows, an optional window facing direction and a monthly comparison from your location and measured obstacle angles.

Inputs of Sun Windows
Field	Type	Default	Description
`day`	date	"2026-06-21"	Date
`latitude`	number	48.89	Latitude
`longitude`	number	8.7	Longitude
`utcOffset`	number	2	UTC offset on selected date
`facing`	number	-1	Window facing (degrees, -1 = open sky)
`stepMinutes`	select (5, 1, 15)	"5"	Sampling interval (minutes)
`obstacles`	table	[{"azimuth":180,"width":40,"height":5,"distance":10}]	Obstacles from the observation point

Example request

Try an example

curl -X POST https://hearthsunwindows.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{}'

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

{
  "mcpServers": {
    "hearth-sun-windows": { "type": "http", "url": "https://hearthsunwindows.usefulweb.app/mcp" }
  }
}