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nkarasiak

QGIS MCP

by nkarasiak

Update Feature Geometry

update_feature_geometry
Destructive

Replace feature geometries in a QGIS layer by supplying feature IDs and WKT coordinates. Changes are undoable inside an edit session.

Instructions

Replace feature geometries. updates: [{fid: 1, geometry_wkt: 'POINT(1 2)'}]. WKT must be in the layer's CRS. Inside an edit session the change is undoable; otherwise it is written straight to the data source.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
updatesYes
layer_idYes
Behavior5/5

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

Despite the destructiveHint annotation, the description adds significant behavioral context: changes are undoable inside an edit session but written directly to the data source otherwise, and WKT must be in the layer's CRS. This goes well beyond the annotation and is critical for safe usage.

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 description is two concise, front-loaded sentences that pack essential information: purpose, example, CRS constraint, and undo behavior. Every sentence adds value with no filler.

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

Completeness5/5

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

For a simple two-parameter tool with no output schema, the description covers all necessary operational details: what it does, the update structure, CRS requirement, and transactional semantics. It is sufficiently complete for an agent to invoke correctly.

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

Parameters4/5

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

The schema has 0% description coverage, but the description compensates by giving a concrete example for the updates parameter ({fid: 1, geometry_wkt: 'POINT(1 2)'}) and stating the CRS requirement. Layer_id is self-explanatory, so overall parameter meaning is sufficiently conveyed, though slightly implicit.

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

Purpose5/5

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

The description clearly states the action 'Replace feature geometries' and provides a concrete example of the update format, which distinguishes it from sibling tools like update_features (attributes). The verb and resource are specific and unambiguous.

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?

The description provides clear context about behavior inside vs. outside an edit session, informing when it is safe to use and when changes are undoable. However, it does not explicitly name alternatives or mention when not to use this tool, so it falls short of a 5.

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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