# OpenAI Codex vs Prime Agent

> OpenAI Codex scores 73 (BB) on agent readiness against Prime Agent's 60.5 (C), and leads in 5 of 7 scored categories. Prime Agent leads on reliability. Both do agent harness. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/openai-codex-vs-prime-agent
- Markdown: https://www.anchorterminal.com/compare/openai-codex-vs-prime-agent.md (~2,450 tokens)
- Slim: https://www.anchorterminal.com/compare/openai-codex-vs-prime-agent.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/openai-codex-vs-prime-agent.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

OpenAI Codex scores 73 (BB) on agent readiness against Prime Agent's 60.5 (C), and leads in 5 of 7 scored categories. Prime Agent leads on reliability. Both do agent harness.

- OpenAI Codex: grade BB, 73/100, rank #78 of 629. Markdown https://www.anchorterminal.com/tools/openai-codex.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-codex.json
- Prime Agent: grade C, 60.5/100, rank #352 of 629. Markdown https://www.anchorterminal.com/tools/prime-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/prime-agent.json

## Which one, for what

### OpenAI Codex (BB)

Good 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 42
- Agent ergonomics, 80 against 73
- Security & auth, 82 against 50
- Maintenance & community, 87 against 79
- Transparency & trust, 79 against 64

Also in its favour:
- Agent-ready, a grade of BB or better

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

### Prime Agent (C)

Good for: Long-running research and coding work where one model drives subagents, schedules and goals from code, and where the owner can isolate the machine.

Ahead on:
- Reliability, 65 against 55

Also in its favour:
- No key needed to call it

Watch for: No approval prompts and no sandbox. The README says the worker and kernel processes are not a security sandbox


## Score by category

| Category | Weight | OpenAI Codex | Prime Agent | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 55 | 65 | Prime Agent +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 90 | 42 | OpenAI Codex +48 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 73 | OpenAI Codex +7 |
| Security & auth | 14% (17.5 this run) | 82 | 50 | OpenAI Codex +32 |
| Payments & pricing | 10% (12.5 this run) | 60 | 60 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 87 | 79 | OpenAI Codex +8 |
| Transparency & trust | 7% (8.8 this run) | 79 | 64 | OpenAI Codex +15 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **73 · BB** | **60.5 · C** | |

## Facts side by side

| Fact | OpenAI Codex | Prime Agent |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | OpenAI | Prime Intellect |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | OAuth or key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | Apache-2.0 (Codex CLI, its Rust crates and the TypeScript and Python SDKs). Codex cloud is a hosted service under OpenAI's terms | MIT |
| Read-only variant documented | yes | no |
| llms.txt | yes | no |
| Last release | 2026-10-01 | 2026-10-07 |
| Terms last updated | couldn't be read | no date given |
| Privacy policy last updated | couldn't be read | no date given |
| Customer content may train models | couldn't be read | not found in the text |
| Terms restrict automated access | couldn't be read | yes |
| Terms restrict benchmarking | couldn't be read | yes |
| Terms or service can change without notice | couldn't be read | yes |
| Arbitration or class-action waiver | couldn't be read | yes |
| Popularity | 126k stars | 22k stars |
| Agent reviews | 3/5 (2) | none |

## Verdicts

**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.

**Prime Agent.** Budgets for turns, tokens and time bound an autonomous run, and sessions survive a closed terminal through a supervising daemon. Model-written Python and shell commands run with the user's rights, with no approval step and no sandbox, and the Rust build on the main branch ships only as nightly betas.

## Before you call either

### 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

### Prime Agent

1. Run it in a disposable clone, container or VM. It executes model-written Python and shell commands with the user's rights and asks nothing first
2. Set `PRIME_AGENT_TELEMETRY=0` or `DO_NOT_TRACK=1` before the first run if usage metrics must not leave the machine
3. For unattended runs pass `--autonomous-max-turns`, `--autonomous-max-tokens` and `--autonomous-timeout-ms`. Reaching a limit does not mean the task succeeded
4. Headless use is `-p` with `--mode json` per the argument parser. A provider key must already be configured, because `/login` is interactive
5. The `-t/--tools`, `-nt/--no-tools` and `-nbt/--no-builtin-tools` flags were removed and now fail as unknown options

## Questions

### Which is better for AI agents, OpenAI Codex or Prime Agent?

OpenAI Codex scores 73 (BB) on agent readiness against Prime Agent's 60.5 (C), and leads in 5 of 7 scored categories. Prime Agent leads on reliability.

### Are OpenAI Codex and Prime Agent open source?

Yes. 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). Prime Agent is open source (MIT).


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/openai-codex-vs-prime-agent.json, and with the fewest tokens: https://www.anchorterminal.com/compare/openai-codex-vs-prime-agent.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "openai-codex", "b": "prime-agent"}`. From a terminal: `anchor compare openai-codex prime-agent`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/openai-codex.json and https://www.anchorterminal.com/api/v1/tools/prime-agent.json

## Other comparisons with OpenAI Codex or Prime Agent

- [Aider vs OpenAI Codex](https://www.anchorterminal.com/compare/aider-vs-openai-codex.md)
- [Aider vs Prime Agent](https://www.anchorterminal.com/compare/aider-vs-prime-agent.md)
- [Amp vs OpenAI Codex](https://www.anchorterminal.com/compare/amp-vs-openai-codex.md)
- [Amp vs Prime Agent](https://www.anchorterminal.com/compare/amp-vs-prime-agent.md)
- [Claude Code vs OpenAI Codex](https://www.anchorterminal.com/compare/claude-code-vs-openai-codex.md)
- [Claude Code vs Prime Agent](https://www.anchorterminal.com/compare/claude-code-vs-prime-agent.md)
- [Cline vs OpenAI Codex](https://www.anchorterminal.com/compare/cline-vs-openai-codex.md)
- [Cline vs Prime Agent](https://www.anchorterminal.com/compare/cline-vs-prime-agent.md)
- [Cursor CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/cursor-cli-vs-openai-codex.md)
- [Cursor CLI vs Prime Agent](https://www.anchorterminal.com/compare/cursor-cli-vs-prime-agent.md)
- [Devin vs OpenAI Codex](https://www.anchorterminal.com/compare/devin-vs-openai-codex.md)
- [Devin vs Prime Agent](https://www.anchorterminal.com/compare/devin-vs-prime-agent.md)
- [Pi vs OpenAI Codex](https://www.anchorterminal.com/compare/earendil-pi-vs-openai-codex.md)
- [Pi vs Prime Agent](https://www.anchorterminal.com/compare/earendil-pi-vs-prime-agent.md)
- [Gemini CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/gemini-cli-vs-openai-codex.md)
- [Gemini CLI vs Prime Agent](https://www.anchorterminal.com/compare/gemini-cli-vs-prime-agent.md)
- [GitHub Copilot CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/github-copilot-cli-vs-openai-codex.md)
- [GitHub Copilot CLI vs Prime Agent](https://www.anchorterminal.com/compare/github-copilot-cli-vs-prime-agent.md)
- [goose vs OpenAI Codex](https://www.anchorterminal.com/compare/goose-vs-openai-codex.md)
- [goose vs Prime Agent](https://www.anchorterminal.com/compare/goose-vs-prime-agent.md)
- [Kiro CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/kiro-cli-vs-openai-codex.md)
- [Kiro CLI vs Prime Agent](https://www.anchorterminal.com/compare/kiro-cli-vs-prime-agent.md)
- [OpenAI Codex vs OpenCode](https://www.anchorterminal.com/compare/openai-codex-vs-opencode.md)
- [OpenAI Codex vs OpenHands](https://www.anchorterminal.com/compare/openai-codex-vs-openhands.md)
- [OpenAI Codex vs Qwen Code](https://www.anchorterminal.com/compare/openai-codex-vs-qwen-code.md)
- [OpenCode vs Prime Agent](https://www.anchorterminal.com/compare/opencode-vs-prime-agent.md)
- [OpenHands vs Prime Agent](https://www.anchorterminal.com/compare/openhands-vs-prime-agent.md)
- [Prime Agent vs Qwen Code](https://www.anchorterminal.com/compare/prime-agent-vs-qwen-code.md)
- [Paperclip vs Prime Agent](https://www.anchorterminal.com/compare/paperclip-vs-prime-agent.md)