arcgis-mcp-bridge

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create_fishnet

Create rectangular fishnet grids for spatial analysis, sampling, or map production using explicit origin, cell dimensions, and grid cell counts.

Instructions

Create a rectangular fishnet or grid feature class using ArcPy CreateFishnet from explicit origin coordinates, optional Y-axis orientation, cell width, cell height, row count, column count, label point option, and output geometry type. Use this to generate sampling grids, planning units, analysis zones, index maps, polygon tiles, or polyline grid overlays before spatial join, summarize-within, raster conversion, QA/QC, or map production. Writes out_features inside a PathGuard allowed root; existing outputs require overwrite=true.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`params`	Yes

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed12 schema fields changedv0.6.3Jul 4, 2026

changedInput schema / $defs / CreateFishnetInput / description

Previous value: -"Input contract for creating a rectangular fishnet/grid feature class."New value: +"Input contract for creating a rectangular fishnet or analysis grid."

changedInput schema / $defs / CreateFishnetInput / properties / cell_height / description

Previous value: -"Height of each fishnet cell in the output coordinate units."New value: +"Height of each fishnet cell in output coordinate system units. Use the same value as cell_width for square cells."

changedInput schema / $defs / CreateFishnetInput / properties / cell_width / description

Previous value: -"Width of each fishnet cell in the output coordinate units."New value: +"Width of each fishnet cell in output coordinate system units. For projected data this is usually meters or feet."

changedInput schema / $defs / CreateFishnetInput / properties / columns / description

Previous value: -"Number of fishnet columns to create."New value: +"Number of fishnet columns to create. Combined with cell_width, this controls the total grid width."

changedInput schema / $defs / CreateFishnetInput / properties / create_label_points / description

Previous value: -"When true, ask ArcPy to create label points for fishnet cells where supported by the geoprocessing tool."New value: +"When true, ask ArcPy CreateFishnet to create label points for grid cells where supported. Use this when cell centers are needed for labels, sampling points, or downstream joins."

changedInput schema / $defs / CreateFishnetInput / properties / geometry_type / description

Previous value: -"Output grid geometry type. POLYGON creates cells as polygons; POLYLINE creates grid lines."New value: +"Output grid geometry type. Use POLYGON when cells should be analysis zones, sampling units, planning units, or overlay features. Use POLYLINE when only grid lines are needed for indexing or cartography."

changedInput schema / $defs / CreateFishnetInput / properties / origin_x / description

Previous value: -"X coordinate of the fishnet origin point."New value: +"X coordinate of the fishnet origin point, usually the lower-left corner of the grid in the output coordinate system."

changedInput schema / $defs / CreateFishnetInput / properties / origin_y / description

Previous value: -"Y coordinate of the fishnet origin point."New value: +"Y coordinate of the fishnet origin point, usually the lower-left corner of the grid in the output coordinate system."

changedInput schema / $defs / CreateFishnetInput / properties / out_features / description

Previous value: -"Absolute output feature class path for the fishnet grid. The path must be inside a configured PathGuard allowed root; existing outputs require overwrite=true."New value: +"Absolute output feature class path for the generated fishnet grid. Use a geodatabase feature class path for project analysis outputs. The path must be inside a configured PathGuard allowed root; existing outputs require overwrite=true."

changedInput schema / $defs / CreateFishnetInput / properties / overwrite / description

Previous value: -"Set true only when replacing an existing output fishnet is intended."New value: +"Set true only when replacing an existing fishnet output feature class is intended."

changedInput schema / $defs / CreateFishnetInput / properties / rows / description

Previous value: -"Number of fishnet rows to create."New value: +"Number of fishnet rows to create. Combined with cell_height, this controls the total grid height."

changedInput schema / $defs / CreateFishnetInput / properties / y_axis_y / description

Previous value: -"Y coordinate of the orientation point used to define the fishnet Y-axis direction. Defaults to origin_y + 10 when omitted."New value: +"Y coordinate of the orientation point used with origin_x to define the fishnet Y-axis direction. Leave None to use origin_y + 10, which creates a north-oriented grid in typical projected coordinate systems."

Changed12 schema fields changedv1.0.1Jul 4, 2026

addedInput schema / $defs / CreateFishnetInput / description

Added value: +"Input contract for creating a rectangular fishnet/grid feature class."

addedInput schema / $defs / CreateFishnetInput / properties / cell_height / description
```
Added value: +"Height of each fishnet cell in the output coordinate units."
```
addedInput schema / $defs / CreateFishnetInput / properties / cell_width / description
```
Added value: +"Width of each fishnet cell in the output coordinate units."
```
addedInput schema / $defs / CreateFishnetInput / properties / columns / description
```
Added value: +"Number of fishnet columns to create."
```

addedInput schema / $defs / CreateFishnetInput / properties / create_label_points / description

Added value: +"When true, ask ArcPy to create label points for fishnet cells where supported by the geoprocessing tool."

addedInput schema / $defs / CreateFishnetInput / properties / geometry_type / description

Added value: +"Output grid geometry type. POLYGON creates cells as polygons; POLYLINE creates grid lines."

addedInput schema / $defs / CreateFishnetInput / properties / origin_x / description
```
Added value: +"X coordinate of the fishnet origin point."
```
addedInput schema / $defs / CreateFishnetInput / properties / origin_y / description
```
Added value: +"Y coordinate of the fishnet origin point."
```

addedInput schema / $defs / CreateFishnetInput / properties / out_features / description

Added value: +"Absolute output feature class path for the fishnet grid. The path must be inside a configured PathGuard allowed root; existing outputs require overwrite=true."

addedInput schema / $defs / CreateFishnetInput / properties / overwrite / description

Added value: +"Set true only when replacing an existing output fishnet is intended."

addedInput schema / $defs / CreateFishnetInput / properties / rows / description
```
Added value: +"Number of fishnet rows to create."
```

changedInput schema / $defs / CreateFishnetInput / properties / y_axis_y / description

Previous value: -"Y of the orientation point; default origin_y+10."New value: +"Y coordinate of the orientation point used to define the fishnet Y-axis direction. Defaults to origin_y + 10 when omitted."

First observedv1.0.0Jul 4, 2026

TDQS

A4/5.0

Behavior3/5

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

Without annotations, the description carries the transparency burden. It discloses that the tool writes outputs to a PathGuard allowed root and requires `overwrite=true` for existing outputs. It does not detail other behavioral traits like error handling or coordinate system behavior, but the core behavior is adequately described.

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 concise at four sentences, front-loading the core function and immediately following with use cases. Every sentence adds value without redundancy or fluff.

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?

The description covers inputs, purpose, and constraints (overwrite, PathGuard). With an output schema present, return values are documented elsewhere. The omission of coordinate system handling is minor and typical for GIS tools.

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?

The input schema already provides detailed descriptions for all parameters, so the description adds only modest additional context (e.g., 'optional Y-axis orientation'). The baseline of 3 is appropriate given the high schema coverage; the description does not significantly enhance parameter understanding.

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 explicitly states the tool's function: creating a rectangular fishnet/grid using ArcPy CreateFishnet with specific inputs. It lists numerous concrete use cases such as sampling grids, planning units, and map production, clearly distinguishing it from sibling tools like 'create_feature_class' or 'dissolve_features'.

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 for when to use this tool: 'before spatial join, summarize-within, raster conversion, QA/QC, or map production.' However, it lacks explicit guidance on when not to use it or alternative approaches, though given the specificity of the tool, this is a minor gap.

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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