tools-only Codex CLI Model Reference
Last updated: 2026-02-26
Current Models
| Model | ID | Released | Description |
|---|---|---|---|
| GPT-5.3-Codex | gpt-5.3-codex |
Feb 5, 2026 | Latest generation. 25% faster than 5.2. Self-bootstrapped (trained partly on its own output). SOTA on SWE-Bench Pro. Default for coding profiles. |
| GPT-5.3-Codex Spark | gpt-5.3-codex-spark |
Feb 5, 2026 | Lightweight variant of 5.3. Near-instant responses. Pro subscribers only. Ideal for quick reads, small reviews, fast iteration. |
| GPT-5.2 | gpt-5.2 |
Dec 2025 | Deeper single-pass reasoning. Default for planning profiles. Community reports fewer cleanup iterations vs 5.3 on complex tasks. |
Deprecated Models
These model IDs no longer work with Codex CLI. Use the current equivalents above.
| Deprecated ID | Era | Replaced By |
|---|---|---|
o3 |
Mid-2025 | gpt-5.3-codex |
o3-mini |
Mid-2025 | gpt-5.3-codex-spark |
o4-mini |
Late 2025 | gpt-5.3-codex-spark |
codex-mini |
Early 2025 | gpt-5.3-codex-spark |
codex-5.2 |
Alias | gpt-5.2 |
gpt-5.1-codex-mini |
Oct 2025 | gpt-5.3-codex-spark |
gpt-5.1-codex-max |
Oct 2025 | gpt-5.3-codex |
Reasoning Effort Levels
Reasoning effort controls how much "thinking" the model does before responding. Higher effort = deeper reasoning but slower and more expensive.
| Level | CLI Value | Use Case |
|---|---|---|
| Minimal | minimal |
Trivial lookups, status checks |
| Low | low |
Simple reads, formatting |
| Medium | medium |
Default interactive coding (speed/quality balance) |
| High | high |
Complex tasks needing deeper reasoning |
| Extra High | xhigh |
Hardest tasks: architecture, multi-file refactors, security audits |
Source: Codex Config Reference — model_reasoning_effort key.
How to Set Reasoning Effort
In ~/.codex/config.toml:
model = "gpt-5.3-codex"
model_reasoning_effort = "xhigh"
Per-invocation via codex-orchestrator:
codex-exec.sh builder "task" --reasoning xhigh
codex-exec.sh planner "task" --reasoning high
Raw Codex CLI:
codex --config model_reasoning_effort='"xhigh"'
codex -c model_reasoning_effort='"xhigh"'
Plan Mode Reasoning
Codex has a separate plan_mode_reasoning_effort config key. When unset, Plan mode defaults to medium. This is independent of model_reasoning_effort.
plan_mode_reasoning_effort = "high"
Configuration
Default model is set in ~/.codex/config.toml:
model = "gpt-5.3-codex"
Override per-invocation with --model and --reasoning:
codex exec --model gpt-5.3-codex-spark "Quick review of auth.ts"
codex exec --model gpt-5.2 "Compare against previous results"
Both codex-orchestrator and codex-cto skills pass --model and -c model_reasoning_effort through to codex exec. Any model ID that Codex CLI accepts will work.
Selection Guide
| Task | Model | Reasoning | Why |
|---|---|---|---|
| Coding subagents (builder, reviewer, debugger, etc.) | gpt-5.3-codex |
xhigh |
Fast execution + maximum reasoning depth |
| Planning subagents (planner, architect, researcher) | gpt-5.2 |
xhigh |
Deeper single-pass reasoning, fewer cleanup iterations |
| Quick reads, fast iteration | gpt-5.3-codex-spark |
medium |
Near-instant, low cost |
| CTO planning (codex-cto) | gpt-5.3-codex |
xhigh |
Architectural reasoning at full capability |
| CTO review (codex-cto) | gpt-5.3-codex |
high |
Diff analysis needs strong but fast reasoning |