set_pyfilter_code · Firegex MCP: Risk & Policy

WHAT IT DOES

What set_pyfilter_code does on Firegex

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

WHY IT NEEDS A POLICY

Why set_pyfilter_code needs a policy

This tool modifies (replaces) Python filter code for a Firegex service. While reversible (another set_pyfilter_code call could restore it), it directly alters the security filtering logic. The high severity reflects that corrupted or malicious filter code could compromise the firewall's ability to protect the system, affecting all traffic through that service.

From the tool's definition Tool name 'set_pyfilter_code' indicates replacement of source code. Description states 'Replace the Python filter source for a service.' This is a write operation that modifies code configuration for an active security service.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_pyfilter_code Rate-limited

set_pyfilter_code 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": {
    "set_pyfilter_code": {
      "limits": [
        {
          "counter": "set_pyfilter_code_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 Firegex, so you can run agents against it safely.

FAQ

Questions about set_pyfilter_code

What does the set_pyfilter_code tool do? +

Replace the Python filter source for a service. It is categorised as a Write tool in the Firegex MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_pyfilter_code? +

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

What risk level is set_pyfilter_code? +

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

Can I rate-limit set_pyfilter_code? +

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

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

set_pyfilter_code is provided by the Firegex MCP server (umbra2728/firegex-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.