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aspect

Idempotent

Calculate downslope azimuth in degrees from a DEM and save as GeoTIFF. Flat cells are marked -1; reproject geographic CRS to projected first.

Instructions

Aspect from a DEM: downslope azimuth in degrees, 0 = north. GeoTIFF in/out.

FLAT CELLS ARE -1, not nodata — mask them before averaging aspect over an area, or the average is plausibly wrong. DEMs in a geographic CRS are refused (see slope): reproject to a projected CRS first. Requires the [whitebox] extra.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "dem_path": "<dem_path>",
      "output_path": "<output_path>"
    },
    "name": "aspect"
  }
}

Input Schema

Name	Required	Description	Default
`dem_path`	Yes
`z_factor`	No
`output_path`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.0Aug 29, 2026

TDQS

A4/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

It discloses non-obvious behaviors beyond the annotations: flat cells are -1 rather than nodata, geographic CRS DEMs are refused, and the whitebox extraction dependency is required. The idempotentHint and destrictiveHint are not contradicted.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The main definition is front-loaded, warnings are clearly separated, and every sentence carries actionable information. It is compact without losing needed context.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present and annotations covering the safety/idempotence profile, the description covers key edge cases, preconditions, and dependencies. The only notable gap is z_factor param semantics, preventing a perfect score.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It does map 'GeoTIFF in/out' to dem_path and output_path, but z_factor is completely undocumented in both the schema and the free-text description, leaving its scaling role unexplained.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description defines the resource and output clearly: 'Aspect from a DEM: downslope azimuth in degrees, 0=north' and 'GeoTIFF in/out'. This distinguishes it from terrain siblings like slope and hillshade, though it lacks an explicit action verb such as 'Computes'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives concrete usage preconditions: mask FLAT cells before averaging, reproject geographic CRS to projected CRS, and install the whitebox extra. It also points to slope for related CRS behavior, but doesn't explicitly state when to prefer a sibling tool over this one.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.