spatial_join · QGIS MCP: Risk & Policy

WHAT IT DOES

What spatial_join does on QGIS MCP

AI agents use spatial_join 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 spatial_join needs a policy

This tool creates or modifies layer attributes reversibly by joining data from one layer to another based on spatial location. While it does not delete data, it writes new attribute data to the target layer. The operation is reversible through undo functionality in QGIS, making it Write rather than Destructive.

From the tool's definition Tool name 'spatial_join' with description 'Join attributes by location (native:joinattributesbylocation)' indicates attribute modification through spatial operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

spatial_join Rate-limited

spatial_join 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": {
    "spatial_join": {
      "limits": [
        {
          "counter": "spatial_join_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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 spatial_join

What does the spatial_join tool do? +

Join attributes by location (native:joinattributesbylocation). 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 spatial_join? +

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

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

Can I rate-limit spatial_join? +

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

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

spatial_join 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.