set_active_workflow · n8n Workflow Builder MCP

WHAT IT DOES

What set_active_workflow does on n8n Workflow Builder

AI agents use set_active_workflow to create or update resources in n8n Workflow Builder — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your n8n Workflow Builder environment.

WHY IT NEEDS A POLICY

Why set_active_workflow needs a policy

This tool creates or modifies session state by designating a workflow as active. It is reversible (another workflow can be set active afterward) and does not delete data or execute arbitrary code. While it affects workflow context, it is not destructive or financial.

From the tool's definition Tool description: 'Set a workflow as the active/current workflow for the session.' This modifies session state by changing which workflow is currently active, which is a reversible state change operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_active_workflow Rate-limited

set_active_workflow 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_active_workflow": {
      "limits": [
        {
          "counter": "set_active_workflow_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches n8n Workflow Builder, so you can run agents against it safely.

FAQ

Questions about set_active_workflow

What does the set_active_workflow tool do? +

📌 Set a workflow as the active/current workflow for the session. It is categorised as a Write tool in the n8n Workflow Builder MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_active_workflow? +

Register the n8n Workflow Builder MCP server in PolicyLayer and add a rule for set_active_workflow: 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 n8n Workflow Builder. Nothing to install.

What risk level is set_active_workflow? +

set_active_workflow is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_active_workflow? +

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

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

set_active_workflow is provided by the n8n Workflow Builder MCP server (schimmilab/n8n-workflow-builder). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.