API & MCP

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

HTTP API

POST https://hearthfrostdates.usefulweb.site/api/v1/calculate – run Frost Dates Finder
GET https://hearthfrostdates.usefulweb.site/api/v1/tool – inputs, output schema, examples
OpenAPI 3.1: /openapi.json · /openapi.yaml
Errors: application/problem+json; 422 includes per-field errors.

Frost Dates Finder

Finds the nearest weather station with frost statistics for 1991–2020 — Deutscher Wetterdienst for Germany, NOAA for the United States — and gives the last spring frost and the first autumn frost at three risk levels, a hard frost and the length of the frost-free season.

Inputs of Frost Dates Finder
Field	Type	Default	Description
`place` (required)	text	"52.47, 13.40"	Place (latitude, longitude). Decimal degrees such as “52.47, 13.40”. Rounded to 0.01° (about 1 km).

Example request

Berlin

curl -X POST https://hearthfrostdates.usefulweb.site/api/v1/calculate -H 'content-type: application/json' -d '{"place":"52.47, 13.40"}'

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://hearthfrostdates.usefulweb.site/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: hearth_frost_dates
Local stdio connector: node src/mcp-stdio.ts --tool=hearth-frost-dates

{
  "mcpServers": {
    "hearth-frost-dates": { "type": "http", "url": "https://hearthfrostdates.usefulweb.site/mcp" }
  }
}