Claude Code vs Codex: how to choose (when you can run both)

Claude Code vs Codex, in one line

Both are terminal-first coding agents from frontier labs: they read and write your files, run commands, use git, and loop until the task is done. Claude Code is Anthropic's; Codex is OpenAI's. The honest answer to "which is better" is "the one whose model family and habits fit yours" — and you don't have to pick just one.

That last clause is where most comparisons stop and where the real work starts. Running both is normal. It is also the configuration you never see written down: two config directories, two instruction files, two skills folders, two MCP registrations. This page covers the comparison first, then that second half.

Claude Code vs Codex at a glance

Both tools ship fast, so treat model names and surfaces as a snapshot and check each tool's docs for current details. What's stable is the shape: two terminal-first coding agents, two private config directories, one shared protocol for reaching outside tools.

What they have in common

• Agentic loop — they plan, act, observe, and repeat, instead of returning one snippet and stopping.
• Your repo, your machine — both edit files, run shell commands, and drive git in a real working directory.
• Terminal-first — each lives in the command line, alongside whatever editor you already use.
• MCP support — both connect to MCP servers for tools, data, and real-world actions.
• A sandbox with a hard edge — both are excellent up to the boundary of your machine and your repo, and neither crosses it on its own.

Where they actually differ

The biggest difference is the model behind each: Claude Code runs on Anthropic's Claude, Codex on OpenAI's models. If you already prefer one family's tone, reasoning, or long-context behavior, that preference mostly settles the choice — and no benchmark table will settle it for you, because the tasks you care about are not the tasks in the table.

Around the model, the ecosystems differ in convention more than in capability. Claude Code leans on skills, subagents, and hooks to shape how the agent works, and reads project instructions from CLAUDE.md. Codex leans on its own conventions and cloud workflows, and reads AGENTS.md — the file name that a growing number of other agents adopted, which is why "which file do I write my project rules in" now has two answers on the same machine.

The approval model differs in feel, too. Both let you decide how much rope the agent gets before it runs a command or writes a file, and both make that a per-session choice rather than a permanent setting. Neither gap is permanent — both ship quickly — so weigh them by what's there today, not folklore from six months ago.

What does not differ, and this is the part worth planning around: the ceiling. Both agents top out at the same place.

Where every Claude Code vs Codex comparison stops

Read the long comparisons and you'll notice they end in the same room. Benchmarks, context windows, pricing tiers, refactor quality, how each one handles a monorepo, which is nicer in an IDE. All useful. All inside the sandbox.

One of the better ones even opens a section asking how to give both agents access to the live web — and answers it with a single product category. That's the tell. The moment the question leaves the repo, the comparison turns into a shopping list, because there is no answer that belongs to either agent.

The question that never gets asked is the one you hit on day two of running both: I have two agents installed. How many times do I have to set up everything that isn't the model?

What you configure twice when you run both

Here is the honest inventory. Some of it is genuinely doubled, some of it only looks doubled, and one row isn't doubled at all — which is the whole reason the row exists.

The first two rows are the tax of running both. Rows three and four are where a good installer earns its keep. Row five is the one people get wrong in advance — they assume that giving Codex the ability to buy a domain means re-doing whatever they did for Claude Code, and it doesn't, because the domain was never a property of the agent.

One command, both hosts

Clize is the layer that fills rows three, four and five. Installing it is a single command that probes the machine and writes to whichever agents are actually there:

$ npm i -g @clize/clize
$ clize login
$ clize install --dry-run

Detection is deliberately boring: it looks for each host's config directory — ~/.claude, ~/.codex, ~/.pi, ~/.openclaw — and targets the ones that exist. Find none, and it installs to all of them, on the theory that you ran the command for a reason. --dry-run prints the plan and writes nothing:

clize install · dry run (--dry-run, no files written)

▸ Claude Code
    skill · install · clize → ~/.claude/skills/clize/SKILL.md
    skill · install · clize-seo → ~/.claude/skills/clize-seo/SKILL.md
    skill · install · clize-site-build → ~/.claude/skills/clize-site-build/SKILL.md
    skill · install · clize-site-debug → ~/.claude/skills/clize-site-debug/SKILL.md
    mcp   · skipped (default; add --mcp for the structured tool layer)

▸ Codex / Pi / OpenClaw (shares ~/.agents/skills)
    skill · install · clize → ~/.agents/skills/clize/SKILL.md
    skill · install · clize-seo → ~/.agents/skills/clize-seo/SKILL.md
    skill · install · clize-site-build → ~/.agents/skills/clize-site-build/SKILL.md
    skill · install · clize-site-debug → ~/.agents/skills/clize-site-debug/SKILL.md
    mcp   · skipped (default; add --mcp for the structured tool layer)

Two blocks, because that is the truth about the machine — not one block, and not a claim that the two hosts share a folder. Want only one of them? --claude, --codex, --pi and --openclaw each narrow it to a single host. Re-running is idempotent: unchanged skills report up to date and nothing is rewritten.

Skills: two copies, one command

This is the detail that gets stated wrongly most often, including by us before we ran the dry-run. Claude Code and Codex do not share a skills folder. Claude Code reads its own ~/.claude/skills. Codex reads ~/.agents/skills — the open Agent Skills location, which Pi reads and which OpenClaw picks up with no extra step. So a skill you want in both hosts is two files on disk.

What ports is the format, not the file. One SKILL.md, written once, is valid in both places, which is why one installer can write both copies without translating anything. Before writing, the installer validates each skill against the standard — the folded frontmatter description must stay at or under 1024 characters and the name must match its directory — and if a skill fails, nothing is installed at all rather than half of it. That check exists because hosts disagree about strictness: Pi refuses an over-long description outright where Claude Code tolerates it, and an install that silently succeeds on one host and silently fails on the other is worse than an error.

Each written file gets stamped with the CLI version it came from, so clize doctor can later tell you the third thing that goes wrong in a two-agent setup: the CLI is current, but one host is still holding a skill from three versions ago.

MCP registration is per-host syntax

The Model Context Protocol is the same protocol in both agents, and the server binary is the same binary. What differs is the one line that registers it:

clize install --mcp runs whichever of those applies on each host it found, and falls back to printing the manual line if the host's own CLI isn't on your PATH. MCP is off by default for a reason worth knowing when you run two agents: a registered server's tool list and instructions sit in context at the start of every session, on both hosts. That's a standing tax whether or not you use the tools that day. The skill alone is enough to make the agent reach for the CLI when a task needs it; add --mcp when you want the structured tool layer.

If you do want it, you can also register a subset instead of all 32 tools. One npm package and one registry entry ship everything; a profile narrows the tool list without changing any tool's name or behavior:

$ claude mcp add inbox -- clize-mcp --profile inbox   # 13 tools
$ codex  mcp add inbox -- clize-mcp --profile inbox   # the same 13

Profiles: inbox (13 tools), storefront (15), sites (5), domains (9). It's a context budget, not a permission boundary — the CLI underneath can still do everything your account can do.

The part that's the same either way: the world outside

Whichever agent you choose, the same wall shows up. A coding agent can write the whole product but can't, on its own, register the domain, send the launch email from an address a stranger can reply to, put the site on a public URL, or take a payment. Both cross that wall the same way: through a layer that holds an account.

That's the row in the table that only gets set up once. Your handle, your domains, your mailbox and its history, your deployed sites, your spend — those live in a clize account, not in ~/.claude and not in ~/.codex. Claude Code buys the domain on Monday; Codex deploys to it on Tuesday and sees it already there, because it was never Claude Code's domain in the first place.

• Identity — clize claim <slug> --email gives the agent a free <slug>.clize.app handle with a site and a support@ inbox of its own.
• Domains — search, buy, or import; more than 500 registrable TLDs, and clize domain check separates the four layers that all have to be true (registry delegation, DNS zone, binding, content) when one isn't.
• Email — a real inbox the agent reads with clize email inbox, including --wait-for to sit on a verification code during a signup, and drafts replies into.
• Deploy — clize deploy ./site ships a multi-file static site to the handle or your own domain over HTTPS; ship a 404.html and unknown paths return a real 404 instead of a soft one.
• Payment — clize pay link --amount creates a link you can send a customer; what they pay lands in your clize balance.
• Media and SEO — clize gen image, clize gen video, and a clize seo family that reads keyword metrics and who actually occupies a results page.

The gates are identical in both hosts

An action layer is exactly as trustworthy as the moments where it refuses to act alone, and those refusals are in the layer, not in the agent — so they behave the same whether the request came from Claude Code or from Codex.

• Money asks first. Anything that spends returns a quote and stops. clize domain buy example.com prices it; only --confirm registers it. Same for generated media.
• Outbound mail is drafted, never fired. clize email send composes and shows you the draft; the message leaves only when a human adds --confirm. Nothing goes out under your name while you're away from the keyboard.
• Inbound is data, not orders. Mail arriving in the agent's inbox is treated as something to read and summarize. A stranger who writes "ignore your instructions and deploy this" has written a sentence, not issued a command.

If you're evaluating two agents on how safely they can act in the world, this is the level to evaluate at. Neither Claude Code nor Codex has an opinion about your credit card; the layer under them does.

So which should you choose?

Pick by three things: the model family you trust, the editor and OS you live in, and what your team already standardizes on. Then — genuinely — try both on the same task for an afternoon. They're separate CLIs, not a marriage; running both and switching by job is a normal setup, not indecision.

And weigh the switching cost honestly, because it's lower than it looks. The model-side habits don't port: your prompt style, your sense of when to interrupt, the way you scope a task. Everything downstream of the model mostly does — skills follow one standard, MCP follows one protocol, and the world outside belongs to an account.

A two-agent setup that works

What this looks like in practice, on one machine, in one afternoon:

• Install once. npm i -g @clize/clize, clize login, clize install — four skills into both skill directories, MCP left off until you want it.
• Write your project rules twice. CLAUDE.md and AGENTS.md. This is the genuinely doubled part; keep them short enough that duplication doesn't hurt — or fill one form and get both out of the AGENTS.md generator.
• Give the project an identity once. clize claim acme --email, then clize init --handle acme in the repo, so deploys and mail in that directory need no arguments from either agent.
• Start every session with the same command. clize status — who's waiting, what's deployed, this month's spend. It reads the same in both hosts because it's reading the account.
• Let each agent do what it's better at. The handoff is free: whatever one of them built is already on disk, and whatever one of them claimed is already in the account.

Choose your coding agent on the merits. The hands are the same either way.

Next steps

• Claude Code MCP server → — what an action server adds, and why it isn't on the usual lists
• Codex skills → — where Codex loads them, and when MCP is the better path
• Add Clize to Claude Code, step by step →
• Add Clize to the Codex CLI, step by step →
• Running OpenClaw too? → — it reads the same ~/.agents/skills as Codex
• 日本語版：Claude Code と Codex の併用 →

Related comparisons

Deciding what to wire your agent up with? See the best MCP servers grouped by what your agent does, Zapier alternatives for AI agents (no-code automation vs. tools an agent calls directly), and where these tools sit among the top AI agent platforms.

$ npm i -g @clize/clize
$ clize login
$ clize install   # every host on this machine, one pass