set_active_layer · QGIS MCP: Risk & Policy

WHAT IT DOES

What set_active_layer does on QGIS MCP

AI agents use set_active_layer 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_active_layer needs a policy

The tool changes application state (which layer is active) rather than performing destructive operations or executing arbitrary code. It's a reversible modification of UI state—switching the active layer back is trivial. While it may enable downstream editing operations, the tool itself only sets focus/state, making it Write rather than Execute.

From the tool's definition Tool description states 'Set the active layer in the QGIS layer panel by layer ID.' This modifies the active state of a UI element, changing which layer is focused for editing or interaction, but does not modify or delete layer data itself.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_active_layer Rate-limited

set_active_layer 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_active_layer": {
      "limits": [
        {
          "counter": "set_active_layer_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_active_layer

What does the set_active_layer tool do? +

Set the active layer in the QGIS layer panel by layer ID. 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_active_layer? +

Register the QGIS MCP server in PolicyLayer and add a rule for set_active_layer: 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_active_layer? +

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

Can I rate-limit set_active_layer? +

Yes. Add a rate_limit block to the set_active_layer 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_active_layer completely? +

Set action: deny in the PolicyLayer policy for set_active_layer. 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_active_layer? +

set_active_layer 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.