# HALOWERK Nordic Land – Mean Surface Slope (Iceland)

> HALOWERK Nordic Land – Mean Surface Slope (Iceland) is a paid API for AI agents from nordland.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).

Returns the mean first-order surface gradient (slope) across the analysis grid for a given coordinate within Iceland.

## Facts

- Endpoint: POST https://nordland.halowerk.com/v1/is-mean-slope
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-nordic-land-mean-surface-slope-iceland-e52b5b40
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5ECxWdqMafojMlV08q1RU

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-nordic-land-mean-surface-slope-iceland-e52b5b40 -d '<json body>'
```

Example prompt: What's the mean surface slope at latitude 64.13, longitude -21.93 in Iceland? I need the terrain gradient for that coordinate.

## When to prefer this

Use this endpoint when you need mean surface slope specifically for coordinates within Iceland, and require boundary-validated, per-call terrain gradient data. Prefer it over generic elevation APIs when you need a processed slope metric rather than raw elevation, and when Iceland-specific boundary validation is important for data quality.

## Known failure modes

- Coordinate outside Iceland's Natural Earth boundary — request rejected before payment
- Latitude or longitude out of published European coverage range (lat 34–72.5, lon -31.5–40.5) — validation error
- Missing or malformed latitude/longitude parameters — input schema validation failure
- Payment failure via x402 protocol — request not processed

## How this service works

Mean first-order surface gradient across the analysis grid. The coordinate is validated against the Natural Earth boundary for Iceland; results outside it are rejected before payment.

## Output

A numeric value representing the mean first-order surface gradient (slope) across the analysis grid for the queried coordinate. Coordinates outside Iceland's Natural Earth boundary are rejected before processing.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "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."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-nordic-land-mean-surface-slope-iceland-e52b5b40/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from nordland.halowerk.com](https://www.zero.xyz/host/nordland.halowerk.com/llms.txt)