codex_query · MCP Coding Agents MCP: Risk & Policy

WHAT IT DOES

What codex_query does on MCP Coding Agents

AI agents invoke codex_query to trigger actions in MCP Coding Agents. 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_query needs a policy

This tool runs queries through the Codex CLI, which is an AI coding agent capable of generating and executing code, shell commands, and file modifications. The CLI tool can perform arbitrary actions on the host system depending on the query content. The server description also highlights 'command execution' as a built-in capability, reinforcing that these agent tools can trigger real operations.

From the tool's definition 'Execute a query using the Codex CLI tool with real-time streaming' — uses 'Execute' and invokes the Codex CLI tool

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

codex_query Rate-limited

codex_query 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_query": {
      "limits": [
        {
          "counter": "codex_query_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 Coding Agents, so you can run agents against it safely.

FAQ

Questions about codex_query

What does the codex_query tool do? +

Execute a query using the Codex CLI tool with real-time streaming. It is categorised as a Execute tool in the MCP Coding Agents 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_query? +

Register the MCP Coding Agents MCP server in PolicyLayer and add a rule for codex_query: 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 Coding Agents. Nothing to install.

What risk level is codex_query? +

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

Can I rate-limit codex_query? +

Yes. Add a rate_limit block to the codex_query 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_query completely? +

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

codex_query is provided by the MCP Coding Agents MCP server (kadreio/mcp-coding-agents). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.