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QGIS MCP

QGIS MCP

by lefcgis
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
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Zonal Statistics

zonal_statistics

Compute per-polygon statistics from a raster layer, including count, sum, mean, median, and more. Add new columns to the polygon layer with a customizable prefix.

Instructions

Per-polygon stats from a raster (native:zonalstatisticsfb). stats int codes: 0=count 1=sum 2=mean 3=median 4=stdev 5=min 6=max 7=range 8=minority 9=majority 10=variety 11=variance (default [0,1,2]). New columns prefixed by 'prefix'. No output_path = in-memory layer.

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": {
      "polygon_layer": "<polygon_layer>",
      "raster_layer": "<raster_layer>"
    },
    "name": "zonal_statistics"
  }
}

Input Schema

NameRequiredDescriptionDefault
bandNo
statsNo
prefixNo_
output_pathNo
raster_layerYes
polygon_layerYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.5.0

TDQS

B3.2/5.0
Behavior3/5

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

Discloses default stats, prefix behavior, and in-memory layer for no output_path. However, lacks details on modification behavior, CRS requirements, or performance implications.

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

Conciseness4/5

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

Very concise, no wasted words. Could be structured slightly better (e.g., separate lines for clarity), but effectively conveys key info in minimal space.

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

Completeness3/5

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

Covers basic functionality and key parameters, but omits details like CRS requirements, side effects on input layers, and output layer creation behavior. Adequate but not comprehensive for a 6-parameter tool with no output schema.

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

Parameters3/5

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

Explains stats codes, prefix, and output_path semantics. Does not explain 'band' parameter; polygon_layer and raster_layer are self-explanatory but lack additional context. Schema coverage is 0%, so description partially compensates.

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?

Description clearly states it computes per-polygon statistics from a raster and identifies the algorithm. However, it does not explicitly differentiate from similar tools like sample_raster_values or spatial_join in sibling list.

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

Usage Guidelines2/5

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

No guidance on when to use this tool versus alternatives such as sample_raster_values or field_calculator. No contextual hints for appropriate scenarios.

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

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