write_hex · Pymcuprog MCP: Risk & Policy

WHAT IT DOES

What write_hex does on Pymcuprog

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

WHY IT NEEDS A POLICY

Why write_hex needs a policy

Based on the tool name 'write_hex' in the context of a microcontroller programming server (pymcuprog), this tool almost certainly writes a hex file to a microcontroller's memory (flash or EEPROM). Writing firmware to hardware is a Write/Execute-level operation with high severity since misuse could brick the device or flash malicious firmware. The description is empty, so confidence is reduced.

From the tool's definition Tool name 'write_hex' on a microcontroller programming server; description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

write_hex Rate-limited

write_hex 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": {
    "write_hex": {
      "limits": [
        {
          "counter": "write_hex_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 Pymcuprog, so you can run agents against it safely.

FAQ

Questions about write_hex

What does the write_hex tool do? +

write_hex. It is categorised as a Write tool in the Pymcuprog MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on write_hex? +

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

What risk level is write_hex? +

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

Can I rate-limit write_hex? +

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

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

write_hex is provided by the Pymcuprog MCP server (lucasgerads/pymcuprog-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.