DeepSeek Harness vs Codex — try your task — AgentSky
DeepSeek Harness vs Codex
Two house pairings: OpenAI's harness on GPT models, DeepSeek's on its own. Your task decides.
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Harness
DeepSeek Model
DeepSeek V4.1 Flash
Harness
Codex Model
GPT-5.6 Sol
Medium Compare agent + model
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Model benchmarks
Artificial Analysis
Intelligence v4.3
General capability across the lab's whole suite.
| Model | Score |
|---|---|
| DeepSeek Harness | DeepSeek V4.1 Flash (Reasoning, Max Effort) |
| Codex | GPT-5.6 Sol (max) |
Coding
The coding subset of the same suite.
| Model | Score |
|---|---|
| DeepSeek Harness | DeepSeek V4.1 Flash (Reasoning, Max Effort) |
| Codex | GPT-5.6 Sol (max) |
Agentic
Tasks the model runs in several steps.
| Model | Score |
|---|---|
| DeepSeek Harness | DeepSeek V4.1 Flash (Reasoning, Max Effort) |
| Codex | GPT-5.6 Sol (max) |
These describe the model on its own, not the harness, the tools or the whole setup this page compares — and the lab runs each model at maximum effort, which is not what the composer above is set to. Scores are only comparable within one index version.
Source: Artificial Analysis — their published model index, taken 2026-09-16.
Agent performance on real tasks
Published Terminal-Bench 4.0 runs. Each result names its tested configuration.
Accuracy · Terminal-Bench 4.0
Percent of trials the whole configuration solved.
| Model | Score |
|---|---|
| DeepSeek Harness | DeepSeek Harness · DeepSeek V4.1 Flash |
| Codex | Codex · GPT-5.6 Sol |
The whisker is the 95% confidence interval. Two configurations whose whiskers overlap are not separated by this benchmark, however far apart their bars look.
Source: Terminal-Bench — their published runs of a harness and model together, taken 2026-09-17.
DeepSeek Harness vs Codex: models, pricing, and features
Compare these configurations on the same task, choose the result you prefer, then continue your chosen session. Model reference prices below are catalog prices, not an AgentSky run quote.
| Configuration | DeepSeek Harness | Codex |
|---|---|---|
| Model | DeepSeek V4.1 Flash | GPT-5.6 Sol |
| Thinking level | Not configurable | Medium |
| Catalog | DeepSeek Harness deepseek/deepseek-v4.1-flash | Codex openai/gpt-5.6-sol |
|---|---|---|
| Input$ / 1M tokens | 0.30 | 2.00 |
| Output$ / 1M tokens | 1.20 | 10.00 |
| Context window tokens | 1.0M | 1.1M |
| Providers serving it | 19 | 3 |
List price for the model alone. What a run from this page costs also depends on the harness, the tools it calls and how long it works.
Source: OpenRouter — the open model catalog, taken 2026-09-17.