trigger_custom_event · HC3 MCP Server MCP: Risk & Policy

WHAT IT DOES

What trigger_custom_event does on HC3 MCP Server

AI agents invoke trigger_custom_event to trigger actions in HC3 MCP Server. 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_custom_event needs a policy

This tool triggers custom events in a Fibaro Home Center 3 system, which can execute automation rules and device actions. While the immediate operation is 'triggering' (not destructive in itself), custom events in home automation systems typically invoke conditional logic that controls physical devices, security systems, and other infrastructure.

From the tool's definition Tool name 'trigger_custom_event' and description 'Trigger a custom event' indicate execution of an event that can have cascading effects through the home automation system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

trigger_custom_event Rate-limited

trigger_custom_event 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_custom_event": {
      "limits": [
        {
          "counter": "trigger_custom_event_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 HC3 MCP Server, so you can run agents against it safely.

FAQ

Questions about trigger_custom_event

What does the trigger_custom_event tool do? +

Trigger a custom event. It is categorised as a Execute tool in the HC3 MCP Server 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_custom_event? +

Register the HC3 MCP Server MCP server in PolicyLayer and add a rule for trigger_custom_event: 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 HC3 MCP Server. Nothing to install.

What risk level is trigger_custom_event? +

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

Can I rate-limit trigger_custom_event? +

Yes. Add a rate_limit block to the trigger_custom_event 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_custom_event completely? +

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

trigger_custom_event is provided by the HC3 MCP Server MCP server (jangabrielsson/hc3_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.