snow_custom_api · Serac MCP: Risk & Policy

WHAT IT DOES

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 IT NEEDS A POLICY

Why snow_custom_api needs a policy

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

Recommended rule Ready

Verdict

snow_custom_api Rate-limited

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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "snow_custom_api": {
      "limits": [
        {
          "counter": "snow_custom_api_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Serac, so you can run agents against it safely.

FAQ

Questions about snow_custom_api

What does the snow_custom_api tool do? +

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.

How do I enforce a policy on snow_custom_api? +

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.

What risk level is snow_custom_api? +

snow_custom_api is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit snow_custom_api? +

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.

How do I block snow_custom_api completely? +

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.

What MCP server provides snow_custom_api? +

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.