fl_append · ArcGIS MCP: Risk & Policy

WHAT IT DOES

What fl_append does on ArcGIS MCP

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

WHY IT NEEDS A POLICY

Why fl_append needs a policy

The prefix 'fl_' likely stands for 'feature layer', and 'append' typically means adding records to an existing dataset. This is a Write operation as appending data is generally reversible (records can be deleted). However, confidence is reduced due to the empty description — it's possible this tool could have destructive overwrite behavior depending on implementation.

From the tool's definition Tool name 'fl_append' suggests appending data to a feature layer, which is a write operation. Description is empty, lowering confidence.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

fl_append Rate-limited

fl_append 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": {
    "fl_append": {
      "limits": [
        {
          "counter": "fl_append_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 ArcGIS MCP, so you can run agents against it safely.

FAQ

Questions about fl_append

What does the fl_append tool do? +

fl_append. It is categorised as a Write tool in the ArcGIS 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 fl_append? +

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

What risk level is fl_append? +

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

Can I rate-limit fl_append? +

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

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

fl_append is provided by the ArcGIS MCP server (renemorenow/arcgis-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.