trigger_flow · ServiceNow- MCP: Risk & Policy

WHAT IT DOES

What trigger_flow does on ServiceNow-MCP

AI agents invoke trigger_flow to trigger actions in ServiceNow-MCP. 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 trigger_flow needs a policy

This tool does not merely read or write data; it triggers external automation logic whose effects depend on supplied parameters. Flow Designer flows can perform system modifications, create records, send notifications, invoke webhooks, or execute scripts—making execution effects non-deterministic and potentially dangerous if parameters are adversarially chosen.

From the tool's definition Tool description states 'Trigger a Flow Designer flow' — flows in ServiceNow can execute arbitrary automations, scripts, API calls, approvals, notifications, and state changes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

trigger_flow Rate-limited

trigger_flow 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": {
    "trigger_flow": {
      "limits": [
        {
          "counter": "trigger_flow_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 ServiceNow-MCP, so you can run agents against it safely.

FAQ

Questions about trigger_flow

What does the trigger_flow tool do? +

Trigger a Flow Designer flow with optional input parameters (requires WRITE_ENABLED=true). It is categorised as a Execute tool in the ServiceNow-MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on trigger_flow? +

Register the ServiceNow- MCP server in PolicyLayer and add a rule for trigger_flow: 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 ServiceNow-MCP. Nothing to install.

What risk level is trigger_flow? +

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

Can I rate-limit trigger_flow? +

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

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

trigger_flow is provided by the ServiceNow- MCP server (tedorigawa001/servicenow-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.