set_scale · Arcmap MCP: Risk & Policy

WHAT IT DOES

What set_scale does on Arcmap

AI agents use set_scale to create or update resources in Arcmap — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Arcmap environment.

WHY IT NEEDS A POLICY

Why set_scale needs a policy

This tool modifies the view state of the active data frame by setting its scale — a reversible change to the map display. It does not delete data, execute arbitrary code, or involve financial operations. It's a Write action (modifying a UI/session state) with low blast radius since it only affects the current map view.

From the tool's definition "Fija la escala del data frame activo y refresca" (Sets the scale of the active data frame and refreshes)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_scale Rate-limited

set_scale 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_scale": {
      "limits": [
        {
          "counter": "set_scale_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 Arcmap, so you can run agents against it safely.

FAQ

Questions about set_scale

What does the set_scale tool do? +

Fija la escala del data frame activo y refresca (ej. 200000 -> 1:200.000). It is categorised as a Write tool in the Arcmap 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_scale? +

Register the Arcmap MCP server in PolicyLayer and add a rule for set_scale: 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 Arcmap. Nothing to install.

What risk level is set_scale? +

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

Can I rate-limit set_scale? +

Yes. Add a rate_limit block to the set_scale 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_scale completely? +

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

set_scale is provided by the Arcmap MCP server (pedralcg/arcmap-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.