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execute_code

Execute PyQGIS code strings to manipulate GIS data, automate spatial analysis, and customize QGIS workflows directly within the software environment.

Instructions

Execute arbitrary PyQGIS code provided as a string.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
codeYes

Implementation Reference

  • Core handler function in the QGIS plugin that executes the provided PyQGIS code using exec() in a safe namespace.
    def execute_code(self, code, **kwargs):
        """Execute arbitrary PyQGIS code"""
        try:
            # Create a local namespace for execution
            namespace = {
                "qgis": Qgis,
                "QgsProject": QgsProject,
                "iface": self.iface,
                "QgsApplication": QgsApplication,
                "QgsVectorLayer": QgsVectorLayer,
                "QgsRasterLayer": QgsRasterLayer,
                "QgsCoordinateReferenceSystem": QgsCoordinateReferenceSystem
            }
            
            # Execute the code
            exec(code, namespace)
            return {"executed": True}
        except Exception as e:
            raise Exception(f"Code execution error: {str(e)}")
  • MCP tool handler that proxies the execute_code command to the QGIS plugin server via socket.
    @mcp.tool()
    def execute_code(ctx: Context, code: str) -> str:
        """Execute arbitrary PyQGIS code provided as a string."""
        qgis = get_qgis_connection()
        result = qgis.send_command("execute_code", {"code": code})
        return json.dumps(result, indent=2)
  • Registration of command handlers in the QGIS plugin server, including execute_code.
    handlers = {
        "ping": self.ping,
        "get_qgis_info": self.get_qgis_info,
        "load_project": self.load_project,
        "get_project_info": self.get_project_info,
        "execute_code": self.execute_code,
        "add_vector_layer": self.add_vector_layer,
        "add_raster_layer": self.add_raster_layer,
        "get_layers": self.get_layers,
        "remove_layer": self.remove_layer,
        "zoom_to_layer": self.zoom_to_layer,
        "get_layer_features": self.get_layer_features,
        "execute_processing": self.execute_processing,
        "save_project": self.save_project,
        "render_map": self.render_map,
        "create_new_project": self.create_new_project,
    }
  • MCP tool registration decorator for execute_code.
    @mcp.tool()
    def execute_code(ctx: Context, code: str) -> str:
        """Execute arbitrary PyQGIS code provided as a string."""
        qgis = get_qgis_connection()
        result = qgis.send_command("execute_code", {"code": code})
        return json.dumps(result, indent=2)
  • Helper method in socket client wrapper for sending execute_code command.
    def execute_code(self, code):
        """Execute arbitrary PyQGIS code"""
        return self.send_command("execute_code", {"code": code})

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observed

TDQS

C2.9/5.0
Behavior2/5

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

No annotations are provided, and the description does not disclose behavioral traits such as side effects, security risks, or what happens to the QGIS state after execution. Given the dangerous nature of arbitrary code execution, this is a significant gap.

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?

The description is a single concise sentence with no unnecessary words. However, given the complexity and risk, a slightly longer description might be warranted, but it is still appropriately sized for a simple tool.

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

Completeness1/5

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

With no output schema, no annotations, and a single parameter lacking description, the tool definition is severely incomplete. It fails to explain return values, error handling, or safety considerations, making it insufficient for an agent to use safely.

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?

The input schema has 0% description coverage for the 'code' parameter. The description only says 'provided as a string' without adding any constraints, expected format, or examples. It adds minimal value beyond the schema.

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 tool executes arbitrary PyQGIS code, which distinguishes it from sibling tools that perform specific QGIS operations like adding layers or rendering maps.

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 like execute_processing. There is no mention of prerequisites, restrictions, or when not to use it.

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