activateReactorWithId

Activates the FusionAuth Reactor using a license Id and optionally a license text (for air-gapped deployments)

SERVERFusionauth SOURCE@fusionauth/mcp-api

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-fusionauth-mcp-api/activatereactorwithid.md

WHAT IT DOES

What activateReactorWithId does on Fusionauth

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

RISK

Why activateReactorWithId is rated Medium

This tool activates a reactor (a premium FusionAuth feature) by writing license configuration to the system. While not destructive (the action is theoretically reversible by deactivation), it creates a material change in system state and licensing posture. The high severity reflects that unauthorized reactor activation could enable unauthorized features or bypass licensing controls.

From the tool's definition Tool description states it 'Activates the FusionAuth Reactor using a license Id' — this modifies system configuration/licensing state. The presence of license parameters indicates data modification that activates a system component.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs activateReactorWithId safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Fusionauth, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For activateReactorWithId, this is the rule to start with:

activateReactorWithId Rate-limited

activateReactorWithId 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": {
    "activateReactorWithId": {
      "limits": [
        {
          "counter": "activatereactorwithid_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Fusionauth, apply this rule, and every activateReactorWithId call is checked against it from then on.

FAQ

Questions about activateReactorWithId

What does the activateReactorWithId tool do? +

Activates the FusionAuth Reactor using a license Id and optionally a license text (for air-gapped deployments). It is categorised as a Write tool in the Fusionauth MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on activateReactorWithId? +

Register the Fusionauth MCP server in PolicyLayer and add a rule for activateReactorWithId: 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 Fusionauth. Nothing to install.

What risk level is activateReactorWithId? +

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

Can I rate-limit activateReactorWithId? +

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

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

activateReactorWithId is provided by the Fusionauth MCP server (@fusionauth/mcp-api). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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