serial_set_rts · MCP Remote Access MCP: Risk & Policy

WHAT IT DOES

What serial_set_rts does on MCP Remote Access

AI agents invoke serial_set_rts to trigger actions in MCP Remote Access. 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 serial_set_rts needs a policy

This tool triggers an external hardware signal (RTS line) on a serial/UART connection, which can cause physical state changes on remote embedded devices — specifically entering bootloader mode. This is an active operation that affects the state of external hardware, making it Execute.

From the tool's definition 'Set RTS (Request To Send) line state. Used for bootloader entry on ESP32/STM32.'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

serial_set_rts Rate-limited

serial_set_rts 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": {
    "serial_set_rts": {
      "limits": [
        {
          "counter": "serial_set_rts_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 MCP Remote Access, so you can run agents against it safely.

FAQ

Questions about serial_set_rts

What does the serial_set_rts tool do? +

Set RTS (Request To Send) line state. Used for bootloader entry on ESP32/STM32. It is categorised as a Execute tool in the MCP Remote Access MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on serial_set_rts? +

Register the MCP Remote Access MCP server in PolicyLayer and add a rule for serial_set_rts: 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 MCP Remote Access. Nothing to install.

What risk level is serial_set_rts? +

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

Can I rate-limit serial_set_rts? +

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

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

serial_set_rts is provided by the MCP Remote Access MCP server (rfingadam/mcp-remote-access). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.