# HALOWERK Land Compare – Rank Sites by Maximum Slope

> HALOWERK Land Compare – Rank Sites by Maximum 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 maximum slope at two to ten named European sites and returns a ranked list with ties preserved.

## Facts

- Endpoint: POST https://landvergleich.halowerk.com/v1/rank-sites-max-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-maximum-slope-bb448c01
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__GURhqjRUCMU62s8D1-qb

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-maximum-slope-bb448c01 -d '<json body>'
```

Example prompt: Rank these five European sites by maximum slope — Monte Baldo (45.72N, 10.85E), Col du Galibier (45.06N, 6.41E), Vercors Plateau (44.94N, 5.53E), Cévennes Ridge (44.18N, 3.67E), and Serra da Estrela (40.32N, -7.61E) — and tell me which is steepest.

## When to prefer this

Use this endpoint when you need to compare and rank terrain steepness across multiple (2–10) named European sites simultaneously and want a single ranked output with ties preserved, rather than fetching individual slope values and sorting them yourself. Prefer this over the two-site signed-difference sibling endpoint when you have more than two candidate locations and need ordinal ranking rather than a pairwise difference score.

## Known failure modes

- Coordinates outside European coverage bounds (lat 34–72.5, lon -31.5–40.5) cause validation errors
- Fewer than 2 or more than 10 locations triggers schema validation failure
- Missing required latitude or longitude for any location returns an error
- Network or upstream DEM data unavailability may cause transient failures
- Malformed location objects with extra properties rejected due to additionalProperties:false

## How this service works

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

## Output

Returns a ranked list of the submitted named sites ordered by their measured maximum slope value, from highest to lowest, with ties preserved using standard dense or competition ranking. Each entry includes the site name, its maximum slope measurement, and its rank position.

## 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-maximum-slope-bb448c01/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)