# HALOWERK Atlantic Land – Netherlands Mean Surface Slope

> HALOWERK Atlantic Land – Netherlands Mean Surface Slope is a paid API for AI agents from atlantikland.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-13).

Returns the mean first-order surface gradient (slope) for a given WGS84 coordinate, validated against the Natural Earth boundary for the Netherlands.

## Facts

- Endpoint: POST https://atlantikland.halowerk.com/v1/nl-mean-slope
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-atlantic-land-netherlands-mean-surface-slope-24f93c9c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_j_lF5nUX_LfJLQScpOiLi

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-atlantic-land-netherlands-mean-surface-slope-24f93c9c -d '<json body>'
```

Example prompt: What is the mean surface slope at latitude 52.37 and longitude 4.90 in the Netherlands? I need the first-order terrain gradient for that location.

## When to prefer this

Choose this endpoint when you need the mean surface terrain slope for a specific point within the Netherlands, especially for land use analysis, construction planning, hydrology, or agricultural assessments. It is purpose-built for the Netherlands with boundary validation, making it more reliable than generic global elevation APIs for Dutch coordinates.

## Known failure modes

- Coordinate outside Netherlands boundary: request rejected before payment with a validation error
- Coordinate outside European coverage bounds (lat 34–72.5, lon -31.5–40.5): rejected at schema validation
- Malformed or missing latitude/longitude fields: schema validation error
- Payment failure via x402 protocol: request not processed
- Server-side computation error for edge-case grid cells near coastlines or borders

## How this service works

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

## Output

A numeric value representing the mean first-order surface gradient (slope) across the analysis grid cell covering the requested coordinate. Coordinates outside the Netherlands boundary are rejected before any payment is charged.

## 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-atlantic-land-netherlands-mean-surface-slope-24f93c9c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from atlantikland.halowerk.com](https://www.zero.xyz/host/atlantikland.halowerk.com/llms.txt)