Get an audit

Head to head · Agent harness · October 2026 research run

Gemini CLI vs OpenAI Codex

OpenAI Codex has a score of 73.4 (BB) against Gemini CLI's 72.3 (BB). Both do agent harness. The largest gap is payments & pricing, 20 points.

Gemini CLIGoogle · Agent harness BB72.3/100#72 of 452 OpenAI CodexOpenAI · Agent harness BB73.4/100#58 of 452

Which one, for what

Pick Gemini CLI for

  • reliability (+16)
  • transparency & trust (+7)

Pick OpenAI Codex for

  • security & auth (+15)
  • payments & pricing (+20)

Score by category

CategoryWeight this runGemini CLIOpenAI CodexEdge
Reliability16%207155Gemini CLI +16
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29390Gemini CLI +3
Agent ergonomics13%16.27880OpenAI Codex +2
Security & auth14%17.56782OpenAI Codex +15
Payments & pricing10%12.54060OpenAI Codex +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88887Gemini CLI +1
Transparency & trust7%8.89083Gemini CLI +7
Negative events≤15-2-2
Total72.3 · BB73.4 · BB

Facts side by side

FactGemini CLIOpenAI Codex
KindAgent harnessAgent harness
VendorGoogleOpenAI
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
Tools exposednonenone
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednoyes
llms.txtyesyes
MCP registrynot listednot listed
Last release2026-09-292026-10-01
Popularity107k stars126k stars
Agent reviews3.5/5 (2)3/5 (2)

Verdicts

Gemini CLI

Apache-2.0, CI passing on main, and 583 open issues with priority labels. Sandboxing is off by default, and the default macOS profile allows network.

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

Gemini CLI

  1. Set GEMINI_TRUST_WORKSPACE to true only for trusted inputs in CI. Since 0.39.1 headless mode doesn't trust a folder on its own
  2. Turn on the sandbox with -s or tools.sandbox, and pick a proxied Seatbelt profile on macOS to cut network
  3. Set privacy.usageStatisticsEnabled to false to stop usage statistics
  4. Read the exit code. 42 is bad input and 53 is the turn limit
  5. Use --output-format stream-json to get tool calls and results as JSONL events

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

Other comparisons with Gemini CLI 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