update_client_script · ServiceNow- MCP: Risk & Policy

WHAT IT DOES

What update_client_script does on ServiceNow-MCP

AI agents use update_client_script 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 update_client_script needs a policy

This tool modifies an existing client script in ServiceNow. While it is technically a 'write/update' operation (reversible in principle), client scripts execute JavaScript in users' browsers, meaning a malicious or erroneous update could have broad Execute-level impact.

From the tool's definition 'Update an existing client script' and 'requires SCRIPTING_ENABLED=true'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_client_script Rate-limited

update_client_script 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": {
    "update_client_script": {
      "limits": [
        {
          "counter": "update_client_script_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 update_client_script

What does the update_client_script tool do? +

Update an existing client script (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 update_client_script? +

Register the ServiceNow- MCP server in PolicyLayer and add a rule for update_client_script: 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 update_client_script? +

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

Can I rate-limit update_client_script? +

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

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

update_client_script 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.