# HALOWERK Southern Land – Portugal Mean Surface Slope

> HALOWERK Southern Land – Portugal Mean Surface Slope is a paid API for AI agents from suedland.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 an analysis grid for a given coordinate within Portugal.

## Facts

- Endpoint: POST https://suedland.halowerk.com/v1/pt-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-southern-land-portugal-mean-surface-slope-25055cd8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LFgdbSwxXpsAyyec5rVLp

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-southern-land-portugal-mean-surface-slope-25055cd8 -d '<json body>'
```

Example prompt: What's the mean surface slope at latitude 38.7, longitude -9.1 in Portugal — I need it for a terrain suitability assessment.

## When to prefer this

Use this endpoint when you need a precise mean surface slope value for a specific geographic coordinate within Portugal. It is ideal for land use planning, agricultural suitability analysis, civil engineering site assessment, environmental modeling, or any workflow that requires terrain steepness data for Portuguese locations. It is preferable over general-purpose elevation APIs when you specifically need a slope gradient metric (not raw elevation) and the location is in Portugal.

## Known failure modes

- Coordinate outside Portugal boundary — request rejected before payment, no charge incurred
- Latitude or longitude outside the declared European coverage range (lat 34–72.5, lon -31.5–40.5) — schema validation failure
- Invalid or missing coordinate fields — 400-level error returned
- Network or service unavailability — timeout or 5xx error

## How this service works

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

## Output

A numeric value representing the mean first-order surface gradient (slope) across the analysis grid centered on the provided coordinate within Portugal. The coordinate is validated against Natural Earth boundaries for Portugal; if it falls outside, the request is rejected before 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-southern-land-portugal-mean-surface-slope-25055cd8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from suedland.halowerk.com](https://www.zero.xyz/host/suedland.halowerk.com/llms.txt)