close_1wire · Buspirate MCP: Risk & Policy

WHAT IT DOES

What close_1wire does on Buspirate

AI agents use close_1wire to create or update resources in Buspirate — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Buspirate environment.

WHY IT NEEDS A POLICY

Why close_1wire needs a policy

The tool modifies hardware state by closing an active 1-Wire communication session and resetting the BusPirate interface mode. This is a reversible write operation—the session can be reopened and the mode can be changed again. It does not irreversibly destroy data (Destructive), execute arbitrary code (Execute), or involve financial operations (Financial).

From the tool's definition Tool description states 'Close a 1-Wire session and reset the BusPirate to HiZ mode' with allowed-write tag. This performs a state change (closing a session, resetting to HiZ mode) that is reversible by opening a new session.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

close_1wire Rate-limited

close_1wire 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": {
    "close_1wire": {
      "limits": [
        {
          "counter": "close_1wire_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 Buspirate, so you can run agents against it safely.

FAQ

Questions about close_1wire

What does the close_1wire tool do? +

Close a 1-Wire session and reset the BusPirate to HiZ mode. [allowed-write] [Duration: instant.]. It is categorised as a Write tool in the Buspirate MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on close_1wire? +

Register the Buspirate MCP server in PolicyLayer and add a rule for close_1wire: 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 Buspirate. Nothing to install.

What risk level is close_1wire? +

close_1wire is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit close_1wire? +

Yes. Add a rate_limit block to the close_1wire 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 close_1wire completely? +

Set action: deny in the PolicyLayer policy for close_1wire. 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 close_1wire? +

close_1wire is provided by the Buspirate MCP server (mplogas/buspirate-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.