set_mode · SmartThings MCP: Risk & Policy

WHAT IT DOES

What set_mode does on SmartThingsMCP

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

WHY IT NEEDS A POLICY

Why set_mode needs a policy

The tool changes location mode, which is a write operation that modifies system state but can be reversed by setting a different mode. While this affects device behavior and automation, it does not delete data (ruling out Destructive), execute arbitrary code (ruling out Execute), or move money (ruling out Financial).

From the tool's definition Tool description states 'Set the current mode for a location' — this modifies location state, a reversible change to configuration.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_mode Rate-limited

set_mode 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_mode": {
      "limits": [
        {
          "counter": "set_mode_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 SmartThingsMCP, so you can run agents against it safely.

FAQ

Questions about set_mode

What does the set_mode tool do? +

Set the current mode for a location. It is categorised as a Write tool in the SmartThingsMCP 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_mode? +

Register the SmartThings MCP server in PolicyLayer and add a rule for set_mode: 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 SmartThingsMCP. Nothing to install.

What risk level is set_mode? +

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

Can I rate-limit set_mode? +

Yes. Add a rate_limit block to the set_mode 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_mode completely? +

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

set_mode is provided by the SmartThings MCP server (technohead/smartthings-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.