apply_style_qml · QGIS MCP: Risk & Policy

WHAT IT DOES

What apply_style_qml does on QGIS MCP

AI agents use apply_style_qml 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 apply_style_qml needs a policy

This tool modifies layer properties (styling) but does not delete data or execute arbitrary code. Style application is reversible—another style can be applied over it. While it affects the map's appearance, the underlying data and features remain intact. This is a Write operation because it updates/modifies layer metadata and rendering configuration.

From the tool's definition The tool applies a QML style file to a layer, which modifies the layer's appearance and styling properties. The description states it 'Apply[s] a QGIS QML style file to a layer,' indicating it changes the layer's visual representation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

apply_style_qml Rate-limited

apply_style_qml 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": {
    "apply_style_qml": {
      "limits": [
        {
          "counter": "apply_style_qml_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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 apply_style_qml

What does the apply_style_qml tool do? +

Apply a QGIS QML style file to a layer. 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 apply_style_qml? +

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

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

Can I rate-limit apply_style_qml? +

Yes. Add a rate_limit block to the apply_style_qml 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 apply_style_qml completely? +

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

apply_style_qml 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.