snow_custom_api
Make an arbitrary REST call to any ServiceNow endpoint with the chosen method (GET/POST/PUT/PATCH/DELETE), path, query params, and JSON body. Escape hatch for endpoints that don
This record as markdown: /tools/serac/snow-custom-api.md
What snow_custom_api does on Serac
AI agents invoke snow_custom_api to trigger actions in Serac. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
Why snow_custom_api is rated High
This tool allows arbitrary REST calls including DELETE, POST, PUT, and PATCH to any ServiceNow endpoint. It spans multiple categories (Read, Write, Destructive) but since it can execute destructive operations (DELETE), trigger workflows, or modify any data, the most severe applicable category is Execute (with Destructive potential). The 'escape hatch' framing confirms it is a catch-all with no guardrails.
From the tool's definition Make an arbitrary REST call to any ServiceNow endpoint with the chosen method (GET/POST/PUT/PATCH/DELETE), path, query params, and JSON body. Escape hatch for endpoints that don
Attacks that exploit this kind of access
The rule that runs snow_custom_api 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_custom_api, this is the rule to start with:
snow_custom_api stays usable, but rate-capped: a runaway agent can't fire it dozens of times 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_custom_api call is checked against it from then on.
Questions about snow_custom_api
Make an arbitrary REST call to any ServiceNow endpoint with the chosen method (GET/POST/PUT/PATCH/DELETE), path, query params, and JSON body. Escape hatch for endpoints that don. It is categorised as a Execute tool in the Serac MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Serac MCP server in PolicyLayer and add a rule for snow_custom_api: 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_custom_api is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the snow_custom_api 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_custom_api. 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_custom_api 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.
More on Serac, and thousands of servers like it.
Across the catalogue