register_event · ServiceNow- MCP: Risk & Policy

WHAT IT DOES

What register_event does on ServiceNow-MCP

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

WHY IT NEEDS A POLICY

Why register_event needs a policy

Registering a custom event in ServiceNow's event registry creates a new, potentially persistent configuration that modifies system behavior. While not immediately destructive or directly executing code, it creates a new entity that could be leveraged for malicious automation or to trigger unwanted workflows.

From the tool's definition Tool name 'register_event' and description 'Register a new custom event in the event registry' indicate creation of a new entity in a system registry. The requirement 'SCRIPTING_ENABLED=true' suggests this enables code execution pathways.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

register_event Rate-limited

register_event 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": {
    "register_event": {
      "limits": [
        {
          "counter": "register_event_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 ServiceNow-MCP, so you can run agents against it safely.

FAQ

Questions about register_event

What does the register_event tool do? +

Register a new custom event in the event registry (requires SCRIPTING_ENABLED=true). It is categorised as a Write tool in the ServiceNow-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 register_event? +

Register the ServiceNow- MCP server in PolicyLayer and add a rule for register_event: 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 ServiceNow-MCP. Nothing to install.

What risk level is register_event? +

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

Can I rate-limit register_event? +

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

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

register_event is provided by the ServiceNow- MCP server (tedorigawa001/servicenow-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.