set_layer_crs · QGIS MCP: Risk & Policy

WHAT IT DOES

What set_layer_crs does on QGIS MCP

AI agents use set_layer_crs 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_layer_crs needs a policy

This tool modifies layer metadata (the CRS property) reversibly. Changing a CRS is a Write operation because it alters data properties but can be undone by setting it back to the original value. The severity is medium because incorrect CRS assignment can corrupt geospatial analyses and render maps incorrectly, but the change is reversible and does not destroy data or execute arbitrary code.

From the tool's definition Tool name 'set_layer_crs' and description 'Set the CRS of a layer' indicate modification of layer properties. CRS (Coordinate Reference System) is a fundamental layer attribute that affects spatial data interpretation and calculations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_layer_crs Rate-limited

set_layer_crs 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_layer_crs": {
      "limits": [
        {
          "counter": "set_layer_crs_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_layer_crs

What does the set_layer_crs tool do? +

Set the CRS of a layer (e.g. 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_layer_crs? +

Register the QGIS MCP server in PolicyLayer and add a rule for set_layer_crs: 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_layer_crs? +

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

Can I rate-limit set_layer_crs? +

Yes. Add a rate_limit block to the set_layer_crs 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_layer_crs completely? +

Set action: deny in the PolicyLayer policy for set_layer_crs. 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_layer_crs? +

set_layer_crs 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.