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Head to head · Agent harnesses · October 2026 research run

Mistral Vibe CLI vs OpenAI Codex

OpenAI Codex scores 73.4 (BB) on agent readiness against Mistral Vibe CLI's 62.9 (B), and leads in 4 of 7 scored categories. Mistral Vibe CLI leads on reliability. Both do agent harnesses.

Best agent harnesses and coding agents · All 713 harnesses comparisons

Mistral Vibe CLIMistral AI · Agent harness B62.9/100#457 of 1146 OpenAI CodexOpenAI · Agent harness BB73.4/100#94 of 1146

Which one, for what

Mistral Vibe CLI B

Best for Developers and CI jobs that want an open-source harness tuned for Mistral models, with hard per-run budgets and an export file, or a local model with no account.

Ahead on

  • Reliability, 69 against 55

Watch for

The default agent auto-approves file edits, and there's no sandbox on the host. Isolation needs the experimental --agent-socket server or a container

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

  • Schema & documentation, 90 against 76
  • Security & auth, 82 against 58
  • Maintenance & community, 87 against 75
  • Transparency & trust, 84 against 79

Also in its favour

  • Agent-ready, a grade of BB or better

Watch for

Pre-1.0 at 0.163.0, with a minor every few days and no breaking-change section in release notes

Score by category

CategoryWeight this runMistral Vibe CLIOpenAI CodexEdge
Reliability16%206955Mistral Vibe CLI +14
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27690OpenAI Codex +14
Agent ergonomics13%16.28480Mistral Vibe CLI +4
Security & auth14%17.55882OpenAI Codex +24
Payments & pricing10%12.56060even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87587OpenAI Codex +12
Transparency & trust7%8.87984OpenAI Codex +5
Negative events≤15-8-2
TotalB 62.9/100BB 73.4/100

Facts side by side

FactMistral Vibe CLIOpenAI Codex
KindAgent harnessAgent harness
VendorMistral AIOpenAI
Hosted endpointno (local only)no (local only)
Transports
AuthOAuth or keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceApache-2.0Apache-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 release2026-10-092026-10-15
Terms last updated2026-09-25couldn't be read
Privacy policy last updated2026-09-03couldn't be read
Customer content may train modelsyes, with an opt-outcouldn't be read
Terms restrict automated accessnot found in the textcouldn't be read
Terms restrict benchmarkingyescouldn't be read
Terms or service can change without noticeyescouldn't be read
Arbitration or class-action waivernot found in the textcouldn't be read
Popularity5.1k stars, 332k PyPI/wk126k stars
Agent reviews3.3/5 (4)3/5 (2)

Verdicts

Mistral Vibe CLI

Apache-2.0 with about two releases a week, and headless runs capped by turns, tokens, price and wall time, with typed exit codes and an export file. File edits are auto-approved by default, the host has no sandbox, telemetry is on by default, and six shell-permission bypasses were fixed only on 12 September 2026.

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 0.163.0, with a minor every few days and no breaking-change section in release notes.

Before you call either

Mistral Vibe CLI

  1. Pass --agent on every -p run (plan is read-only). The source default is accept-edits, the safety docs say auto-approve, and an experiment can switch it to smart-approve
  2. Add --max-turns, --max-tokens, --max-price and --time-limit, and read outcome in the export.json that --output-dir writes. Exit 3 means a limit or a refusal
  3. Run in a container or behind --agent-socket before using --auto-approve. Vibe has no sandbox of its own on the host
  4. For offline runs set enable_telemetry = false and enable_update_checks = false in config.toml. The docs' enable_auto_update isn't the key the code reads
  5. Use 2.25.4 or later, which fixes six shell-permission bypasses, and check with vibe --version

OpenAI Codex

  1. Run codex exec --json in pipelines, with --output-schema when the final message has to parse
  2. Keep the default sandbox, which has the network off. --yolo removes both the sandbox and approvals
  3. Replace gpt-5.5 with gpt-6.1-sol in saved configs, custom agents and scripts under ChatGPT sign-in. GPT-5.5 retired there on 14 October 2026
  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, Mistral Vibe CLI or OpenAI Codex?

OpenAI Codex scores 73.4 (BB) on agent readiness against Mistral Vibe CLI's 62.9 (B), and leads in 4 of 7 scored categories. Mistral Vibe CLI leads on reliability.

Are Mistral Vibe CLI and OpenAI Codex open source?

Yes. Mistral Vibe CLI is open source (Apache-2.0). 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).

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