# HALOWERK Land Compare – Rank Sites by Mean Slope

> HALOWERK Land Compare – Rank Sites by Mean Slope is a paid API for AI agents from landvergleich.halowerk.com, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-15).

Measures mean terrain slope for two to ten named European sites and returns a ranked list with ties preserved.

## Facts

- Endpoint: POST https://landvergleich.halowerk.com/v1/rank-sites-mean-slope
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-land-compare-rank-sites-by-mean-slope-42572374
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EX4_Iq1PqhPCUHBVL9oit

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-land-compare-rank-sites-by-mean-slope-42572374 -d '<json body>'
```

Example prompt: Can you rank these five European sites by their mean slope — Tuscany Hills at 43.2°N 11.4°E, Ardennes Plateau at 50.1°N 5.7°E, Andalusian Valley at 37.5°N -4.8°E, Danube Lowland at 47.8°N 18.9°E, and Paris Basin at 48.7°N 2.4°E — steepest to flattest?

## When to prefer this

Use this endpoint when you need to compare and rank mean slope values across two to ten named European sites in a single call, with ties handled automatically. Prefer it over pairwise comparison endpoints when you have three or more sites to rank, or when you need an ordered list rather than just a signed difference between two points.

## Known failure modes

- Coordinates outside the European coverage window (lat 34–72.5°N, lon -31.5–40.5°E) cause a validation error
- Fewer than two or more than ten locations in the request array cause a schema validation failure
- Missing required latitude or longitude fields for any item cause a 400-level error
- Payment failure or missing x402 payment header results in a 402 response
- Network timeout on the backend terrain data source may return a 503 or 504

## How this service works

Measures mean slope for two to ten named European sites and ranks the observed values with ties preserved.

## Output

Returns each named site with its computed mean slope value and an ordinal rank (ties are preserved with shared rank positions), allowing direct comparison of terrain steepness across the submitted European locations.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "locations": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "longitude",
     "latitude"
    ],
    "properties": {
     "name": {
      "type": "string",
      "maxLength": 60,
      "minLength": 1
     },
     "latitude": {
      "type": "number",
      "maximum": 72.5,
      "minimum": 34,
      "description": "WGS84 latitude inside the published European coverage."
     },
     "longitude": {
      "type": "number",
      "maximum": 40.5,
      "minimum": -31.5,
      "description": "WGS84 longitude inside the published European coverage."
     }
    },
    "additionalProperties": false
   },
   "maxItems": 10,
   "minItems": 2
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-land-compare-rank-sites-by-mean-slope-42572374/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from landvergleich.halowerk.com](https://www.zero.xyz/host/landvergleich.halowerk.com/llms.txt)