codex_review · Codex MCP: Risk & Policy

WHAT IT DOES

What codex_review does on Codex

AI agents invoke codex_review to trigger actions in Codex. 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 codex_review needs a policy

This tool executes a code review operation via the Codex CLI. Even though code review is technically an analytical operation, it invokes an external system (Codex) to perform work whose effects and side effects depend on what code is submitted for review and how Codex processes it. The 5-minute timeout indicates a long-running synchronous operation.

From the tool's definition Tool is described as 'Run a Codex code review SYNCHRONOUSLY' and is part of a server that 'exposing 8 Codex tools (exec, review, skill list, skill run, status, poll, list jobs, kill)'.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

codex_review Rate-limited

codex_review 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": {
    "codex_review": {
      "limits": [
        {
          "counter": "codex_review_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 Codex, so you can run agents against it safely.

FAQ

Questions about codex_review

What does the codex_review tool do? +

Run a Codex code review SYNCHRONOUSLY (with a 5-min timeout). It is categorised as a Execute tool in the Codex MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on codex_review? +

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

What risk level is codex_review? +

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

Can I rate-limit codex_review? +

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

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

codex_review is provided by the Codex MCP server (pigowenhsiao/codex-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.