apply_map_theme · QGIS MCP: Risk & Policy

WHAT IT DOES

What apply_map_theme does on QGIS MCP

AI agents use apply_map_theme 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_map_theme needs a policy

Applying a map theme reversibly modifies the QGIS project's visual state by changing which layers are visible. This is a configuration change that affects the project state but does not create, destroy, or execute arbitrary operations. It falls under Write (reversible modification) rather than Execute or Destructive.

From the tool's definition Tool description states it 'Apply a map theme — restores the layer visibility state saved in the theme.' This modifies the current visualization state (layer visibility) without creating or deleting data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

apply_map_theme Rate-limited

apply_map_theme 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_map_theme": {
      "limits": [
        {
          "counter": "apply_map_theme_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_map_theme

What does the apply_map_theme tool do? +

Apply a map theme — restores the layer visibility state saved in the theme. 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_map_theme? +

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

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

Can I rate-limit apply_map_theme? +

Yes. Add a rate_limit block to the apply_map_theme 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_map_theme completely? +

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

apply_map_theme 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.