API & MCP

Everything a person can do on GISela Area & Length, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://giselaarealength.usefulweb.site/api/v1/calculate – run GISela Area & Length
GET https://giselaarealength.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.

GISela Area & Length

Measures every polygon and line of GeoJSON, KML, GPX, CSV/WKT or shapefile data on the WGS 84 ellipsoid with Karney’s geodesic algorithms — the same numbers as GISela’s measure tool and attribute fields. Holes are subtracted; results in metric or imperial units.

Inputs of GISela Area & Length
Field	Type	Default	Description
`data`	textarea	—	Data. GeoJSON, TopoJSON, KML, GPX, CSV (lat/lon, x/y or a WKT column) or WKT lines. Or upload a file below.
`file`	file	—	File (optional). Used instead of the pasted text. Shapefiles: put .shp, .dbf and .prj into one ZIP.
`from`	text	"auto"	Coordinate system of the data. “auto” reads it from the file (.prj, GeoJSON crs); otherwise an EPSG code such as 2056, 25832 or 27700. Without information the data is read as WGS 84 longitude/latitude.
`units`	select (metric, imperial)	"metric"	Units

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://giselaarealength.usefulweb.site/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: gisela_area_length
Local stdio connector: node src/mcp-stdio.ts --tool=gisela-area-length

{
  "mcpServers": {
    "gisela-area-length": { "type": "http", "url": "https://giselaarealength.usefulweb.site/mcp" }
  }
}