snow_error_handler
Register a server-side error handler (sys_error_handler) bound to a specific error type. The handler_script runs when that error fires; must be ES5-compatible (no arrow functions, const/let, etc.).
This record as markdown: /tools/serac/snow-error-handler.md
What snow_error_handler does on Serac
AI agents use snow_error_handler to create or update resources in Serac, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Serac environment.
Why snow_error_handler is rated Medium
This tool creates new error handler records and modifies ServiceNow's error handling behavior by registering handler_script code that executes on specific error types. While it writes configuration rather than deleting it, the ability to inject arbitrary server-side scripts (handler_script) that run automatically on errors poses significant risk if misused—an attacker could inject malicious logic into error paths to…
From the tool's definition Tool registers a server-side error handler (sys_error_handler) and executes handler_script code on error events. Creates or modifies error handling configuration in ServiceNow.
Attacks that exploit this kind of access
The rule that runs snow_error_handler safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Serac, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For snow_error_handler, this is the rule to start with:
snow_error_handler 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Serac, apply this rule, and every snow_error_handler call is checked against it from then on.
Questions about snow_error_handler
Register a server-side error handler (sys_error_handler) bound to a specific error type. The handler_script runs when that error fires; must be ES5-compatible (no arrow functions, const/let, etc.). It is categorised as a Write tool in the Serac MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Serac MCP server in PolicyLayer and add a rule for snow_error_handler: 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 Serac. Nothing to install.
snow_error_handler 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 snow_error_handler 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 snow_error_handler. 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.
snow_error_handler is provided by the Serac MCP server (serac-labs/serac). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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