close_uart · Buspirate MCP: Risk & Policy

WHAT IT DOES

What close_uart does on Buspirate

AI agents use close_uart 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_uart needs a policy

Closing a UART session and finalizing logs constitutes a reversible write operation—it terminates an active communication channel and commits session data. This is a normal cleanup/teardown action with no destructive or irreversible consequences. The low severity reflects that the primary effect is graceful session termination, which is safe and expected behavior in hardware communication workflows.

From the tool's definition Tool name is 'close_uart' with description 'Close a UART session and finalize logs.' The 'close' operation and 'finalize logs' indicate state modification of an active session, aligned with the [allowed-write] tag in the description.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

close_uart Rate-limited

close_uart 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_uart": {
      "limits": [
        {
          "counter": "close_uart_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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_uart

What does the close_uart tool do? +

Close a UART session and finalize logs. [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_uart? +

Register the Buspirate MCP server in PolicyLayer and add a rule for close_uart: 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_uart? +

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

Can I rate-limit close_uart? +

Yes. Add a rate_limit block to the close_uart 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_uart completely? +

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

close_uart 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.