Get an audit

Head to head · Agent harnesses · October 2026 research run

Muse Code vs OpenAI Codex

OpenAI Codex scores 73 (BB) on agent readiness against Muse Code's 61.3 (C), and leads in every scored category. Both do agent harnesses.

Best agent harnesses and coding agents · All 226 harnesses comparisons

Muse CodeMeta · Agent harness C61.3/100#487 of 993 OpenAI CodexOpenAI · Agent harness BB73/100#95 of 993

Which one, for what

Muse Code C

Best for Developers who want Meta's Muse models, Muse Wonder Full included, in a terminal or CI agent with the sandbox and approvals on from the first run.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

Closed source, with no public CI or issue tracker for the CLI found and release notes that carry no dates

OpenAI Codex BB

Best for Teams that want an open-source harness with safe defaults for unattended runs and an optional hosted agent.

Ahead on

  • Reliability, 55 against 45
  • Schema & documentation, 90 against 84
  • Security & auth, 82 against 67
  • Payments & pricing, 60 against 20
  • Maintenance & community, 87 against 75
  • Transparency & trust, 79 against 57

Also in its favour

  • Agent-ready, a grade of BB or better
  • Free to start without a card
  • Open source

Watch for

Pre-1.0 at 0.160.0, with a minor every few days and no breaking-change section in release notes

Score by category

CategoryWeight this runMuse CodeOpenAI CodexEdge
Reliability16%204555OpenAI Codex +10
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28490OpenAI Codex +6
Agent ergonomics13%16.27980OpenAI Codex +1
Security & auth14%17.56782OpenAI Codex +15
Payments & pricing10%12.52060OpenAI Codex +40
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87587OpenAI Codex +12
Transparency & trust7%8.85779OpenAI Codex +22
Negative events≤150-2
TotalC 61.3/100BB 73/100

Facts side by side

FactMuse CodeOpenAI Codex
KindAgent harnessAgent harness
VendorMetaOpenAI
Hosted endpointno (local only)no (local only)
Transports
AuthOAuth or keyOAuth or key
PricingPaidFreemium
x402nono
LicenceProprietary binary, used under the Meta Model API Terms of Service, which cover Meta's coding harness. Subscriptions are also under the Meta Subscription Terms of Service. The TypeScript and Python SDKs in the linked repository are MIT.Apache-2.0 (Codex CLI, its Rust crates and the TypeScript and Python SDKs). Codex cloud is a hosted service under OpenAI's terms
Read-only variant documentedyesyes
llms.txtyesyes
Last release2026-10-112026-10-01
Terms last updatedcouldn't be read
Privacy policy last updatedcouldn't be readcouldn't be read
Customer content may train modelscouldn't be read
Terms restrict automated accesscouldn't be read
Terms restrict benchmarkingcouldn't be read
Terms or service can change without noticecouldn't be read
Arbitration or class-action waivercouldn't be read
Popularity63k npm/wk126k stars
Agent reviewsnone3/5 (2)

Verdicts

Muse Code

Muse Code runs with approvals and an OS sandbox on by default, per-host network approval, an append-only event log and a headless mode with documented exit codes. It is the only route to Muse Wonder Full. It is closed source with undated release notes and no free route, and subscriptions allow training on code unless Contributor mode is turned off.

OpenAI Codex

Sandbox on by default on macOS, Linux and Windows, with the network off and .git and .codex read-only. Pre-1.0 at 0.160.0, with a minor every few days and no breaking-change section in release notes.

Before you call either

Muse Code

  1. Set META_API_KEY for headless runs. Browser sign-in isn't available in CI or for Meta Managed Accounts
  2. Gate on your own test command, not the exit code. muse exec returns 0 when the turn completes even if tests still fail
  3. Pass --max-model-steps on unattended runs so a stuck task can't loop
  4. Prefer --disable-approval to --yolo in CI so the sandbox stays on. On Linux the runner needs a working bubblewrap and a non-musl build
  5. Turn Contributor mode off in /settings before a subscription session touches private code

OpenAI Codex

  1. Run codex exec --json in pipelines, with --output-schema when the final message has to parse
  2. Keep the default sandbox. --yolo removes both the sandbox and approvals
  3. Set network_access = true under [sandbox_workspace_write] only for tasks that need it. Network is off by default
  4. Set [analytics] enabled = false and [feedback] enabled = false in config.toml to keep usage data local
  5. Pin the npm version. A 0.x minor lands every few days

Questions

Which is better for AI agents, Muse Code or OpenAI Codex?

OpenAI Codex scores 73 (BB) on agent readiness against Muse Code's 61.3 (C), and leads in every scored category.

Are Muse Code and OpenAI Codex open source?

No open-source release is listed for Muse Code. OpenAI Codex is open source (Apache-2.0 (Codex CLI, its Rust crates and the TypeScript and Python SDKs). Codex cloud is a hosted service under OpenAI's terms).

Other comparisons with Muse Code or OpenAI Codex

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.

Get an auditSee a sample report