install_from_app_repo

THE RISK

Medium Risk

Why install_from_app_repo needs a policy

Installing an application creates and modifies configuration and code within the ServiceNow instance, making it a Write operation. While installation could have significant side effects on system functionality, it is reversible (applications can be uninstalled). This falls short of Destructive (irreversible) or Execute (arbitrary code execution with unpredictable effects).

From the tool's definition The tool name 'install_from_app_repo' indicates installation of an application, which is a write operation that creates or modifies the system state.

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

POLICY

How to control install_from_app_repo

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 install_from_app_repo:

policy.json

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

install_from_app_repo 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

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

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 install_from_app_repo

What does the install_from_app_repo tool do? +

Install an application from the company. 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 install_from_app_repo? +

Register the Now Sdk Ext MCP server in PolicyLayer and add a rule for install_from_app_repo: 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 install_from_app_repo? +

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

Can I rate-limit install_from_app_repo? +

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

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

install_from_app_repo 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 →