set_canvas_extent · QGIS MCP: Risk & Policy

WHAT IT DOES

What set_canvas_extent does on QGIS MCP

AI agents use set_canvas_extent to create or update resources in QGIS MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your QGIS MCP environment.

WHY IT NEEDS A POLICY

Why set_canvas_extent needs a policy

This tool modifies the canvas display state (extent/zoom level) but does not create, delete, or execute arbitrary commands. It's a Write operation because it changes map configuration reversibly. Severity is medium because misuse could cause disorientation or obscure important features, but the effect is limited to the current view state and does not affect underlying data or trigger external processes.

From the tool's definition Tool description states 'Set the map canvas extent' — a modification operation that changes the visible area of the map canvas. This is a reversible state change to the map view.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_canvas_extent Rate-limited

set_canvas_extent stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_canvas_extent": {
      "limits": [
        {
          "counter": "set_canvas_extent_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches QGIS MCP, so you can run agents against it safely.

FAQ

Questions about set_canvas_extent

What does the set_canvas_extent tool do? +

Set the map canvas extent. Coordinates should be in the specified CRS (default: project CRS). It is categorised as a Write tool in the QGIS MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_canvas_extent? +

Register the QGIS MCP server in PolicyLayer and add a rule for set_canvas_extent: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches QGIS MCP. Nothing to install.

What risk level is set_canvas_extent? +

set_canvas_extent is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_canvas_extent? +

Yes. Add a rate_limit block to the set_canvas_extent rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block set_canvas_extent completely? +

Set action: deny in the PolicyLayer policy for set_canvas_extent. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides set_canvas_extent? +

set_canvas_extent is provided by the QGIS MCP server (nkarasiak/qgis-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.