set_current_update_set

THE RISK

Medium Risk

Why set_current_update_set needs a policy

This tool modifies session state by setting the active update set, which directs where subsequent changes are recorded in ServiceNow. While it does not directly delete or execute arbitrary code, it alters the system's configuration for the current session, determining which update set will capture modifications. This is a reversible Write operation—the update set can be changed again.

From the tool's definition Set the active update set for the session. All changes will be captured in this update set.

Documented attack patterns abuse exactly the kind of access set_current_update_set gives an agent:

POLICY

How to control set_current_update_set

PolicyLayer is an MCP gateway — it sits between your AI agents and Now Sdk Ext, and nothing reaches the server without passing your rules. This is the rule we recommend for set_current_update_set:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_current_update_set": {
      "limits": [
        {
          "counter": "set_current_update_set_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

set_current_update_set 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.

Create a free account and register Now Sdk Ext — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Now Sdk Ext tools

Destructive cancel_flow Cancel a running or paused flow execution by its context ID. Destructive query_delete_records Find records matching an encoded query and delete them all. Execute aggregate_grouped Run aggregate functions (COUNT, AVG, MIN, MAX, SUM) grouped by a field on any Execute execute_action Execute a ServiceNow Flow Designer action by scoped name. Execute execute_flow Execute a published ServiceNow Flow Designer flow by scoped name. Execute execute_script Execute JavaScript on a ServiceNow instance using Scripts - Background Execute execute_subflow Execute a ServiceNow Flow Designer subflow by scoped name. Execute run_atf_test Execute a single ServiceNow ATF (Automated Test Framework) test by its sys_id.

All 86 Now Sdk Ext tools →

Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about set_current_update_set

What does the set_current_update_set tool do? +

Set the active update set for the session. All changes will be captured in this update set. It is categorised as a Write tool in the Now Sdk Ext 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_current_update_set? +

Register the Now Sdk Ext MCP server in PolicyLayer and add a rule for set_current_update_set: 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 Now Sdk Ext. Nothing to install.

What risk level is set_current_update_set? +

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

Can I rate-limit set_current_update_set? +

Yes. Add a rate_limit block to the set_current_update_set 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_current_update_set completely? +

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

set_current_update_set is provided by the Now Sdk Ext MCP server (sonisoft-cnanda/now-sdk-ext-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Now Sdk Ext tool call.

Start from Now Sdk Ext, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →