codex

Codex CLI

Agent ID: codex

OpenAI's Codex CLI. Speaks ACP via the @zed-industries/codex-acp bridge, which is bundled with agents-wire (no peer install needed).

Install

Install the Codex CLI and set your API key:

npm install -g @openai/codex
export OPENAI_API_KEY="sk-..."

Quick Start

import { agents } from "@pivanov/agents-wire";

const result = await agents.ask(
  "codex",
  "Refactor src/auth.ts",
  {
    permission: "auto-allow",
  },
);

console.log(result.text);

Model Selection

options.model becomes -c model="X" on the codex-acp CLI (verified via codex-acp --help). This is the most reliable model selection path of all built-in agents.

options.effort becomes -c model_reasoning_effort="X". Valid values are "low", "medium", and "high". Only applies to reasoning models (o3, o1).

await agents.ask(
  "codex",
  prompt,
  {
    model: "gpt-5",
  },
);
await agents.ask(
  "codex",
  prompt,
  {
    model: "o3",
  },
);

// Reasoning effort (o3, o1 only):
await agents.ask(
  "codex",
  prompt,
  {
    model: "o3",
    effort: "low",
  },
);
await agents.ask(
  "codex",
  prompt,
  {
    model: "o3",
    effort: "high",
  },
);

Capabilities

Feature	Supported
ask / stream / session	✅
askJson	✅
MCP stdio	✅
MCP http/sse	❌
Session listing (listSessions)	✅
Tool call interception	✅

Cost Tracking

Codex reports per-turn costUsd. Full cost tracking and maxCostUsd budget enforcement work.

Auth Failure Detection

If OPENAI_API_KEY is missing or invalid, the SDK catches the authentication-failure pattern in stderr and throws AgentUnauthenticatedError.

Gotchas

• Requires a POSIX environment (macOS, Linux, WSL).
• The OPENAI_API_KEY must be set in the environment. Pass custom env vars via options.envFilter.