Updates an existing variable on a service catalog item's form.
AI agents use update_catalog_item_variable to create or update resources in Snow — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Snow environment.
This tool modifies existing configuration data (catalog item variables/form fields) but does not delete, execute code, move money, or trigger irreversible operations. It fits the Write category as it creates or modifies data reversibly.
From the tool's definition The tool name contains 'update' and the description states it 'Updates an existing variable on a service catalog item's form.' This is a reversible modification operation that changes data in ServiceNow's service catalog.
Documented attack patterns abuse exactly the kind of access update_catalog_item_variable gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Snow, and nothing reaches the server without passing your rules. This is the rule we recommend for update_catalog_item_variable:
{
"version": "1",
"default": "deny",
"tools": {
"update_catalog_item_variable": {
"limits": [
{
"counter": "update_catalog_item_variable_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_catalog_item_variable 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.
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Updates an existing variable on a service catalog item's form. It is categorised as a Write tool in the Snow MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Snow MCP server in PolicyLayer and add a rule for update_catalog_item_variable: 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 Snow. Nothing to install.
update_catalog_item_variable is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the update_catalog_item_variable 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.
Set action: deny in the PolicyLayer policy for update_catalog_item_variable. 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.
update_catalog_item_variable is provided by the Snow MCP server (shunyaai/snow-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Snow, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
88 Snow tools catalogued and risk-classified — across an index of 43,000+ MCP servers.