select_serial_port · ESP-IDF FastMCP Server MCP

WHAT IT DOES

What select_serial_port does on ESP-IDF FastMCP Server

AI agents use select_serial_port to create or update resources in ESP-IDF FastMCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your ESP-IDF FastMCP Server environment.

WHY IT NEEDS A POLICY

Why select_serial_port needs a policy

This tool modifies the selected/active serial port configuration, making it a Write operation. It is not destructive (the change is reversible by selecting a different port), not financial, and not Execute (it doesn't run commands or trigger external operations—it only changes which port is targeted).

From the tool's definition Tool description states 'Select a target serial port for ESP-IDF operations.' The verb 'select' indicates modifying configuration state (which serial port is currently active), which is a reversible write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

select_serial_port Rate-limited

select_serial_port 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": {
    "select_serial_port": {
      "limits": [
        {
          "counter": "select_serial_port_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 ESP-IDF FastMCP Server, so you can run agents against it safely.

FAQ

Questions about select_serial_port

What does the select_serial_port tool do? +

Select a target serial port for ESP-IDF operations. It is categorised as a Write tool in the ESP-IDF FastMCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on select_serial_port? +

Register the ESP-IDF FastMCP Server MCP server in PolicyLayer and add a rule for select_serial_port: 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 ESP-IDF FastMCP Server. Nothing to install.

What risk level is select_serial_port? +

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

Can I rate-limit select_serial_port? +

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

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

select_serial_port is provided by the ESP-IDF FastMCP Server MCP server (jasper-zsh/espidf-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.