device_primary_set · Yaver MCP: Risk & Policy

WHAT IT DOES

What device_primary_set does on Yaver

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

PARAMETERS

Parameter	Type	Required	Description
`clear`	boolean	—	Unset the preference instead of picking a device.
`deviceId`	string	—	Full deviceId or unique prefix. Ignored when clear=true.

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why device_primary_set needs a policy

An AI agent can call device_primary_set faster than any human can review — one bad instruction and it creates or modifies resources in Yaver by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

device_primary_set Rate-limited

device_primary_set 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": {
    "device_primary_set": {
      "limits": [
        {
          "counter": "device_primary_set_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 Yaver, so you can run agents against it safely.

FAQ

Questions about device_primary_set

What does the device_primary_set tool do? +

Mark a device as the primary (auto-connect) target. Accepts a deviceId or unique prefix. Pass clear:true instead to unset the preference. It is categorised as a Write tool in the Yaver MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does device_primary_set accept? +

device_primary_set accepts 2 parameters: clear, deviceId. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on device_primary_set? +

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

What risk level is device_primary_set? +

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

Can I rate-limit device_primary_set? +

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

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

device_primary_set is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.