Tier A: Strong with clear operating rules.
GPT 5.5
Excellent planner, risky for long-horizon coding.
Our take
GPT 5.5 writes clean code and fits OpenAI tooling well, but can overthink, add unasked-for features, and burn context on long builds.
Best for
- Plan mode
- Architecture drafts
- OpenAI-native workflows
- Shorter coding tasks
Watch out
- Reasoning overhead can fill context
- Can drift without explicit goals
- May add features you did not ask for
Why it is ranked here
- The video praises its plan mode as one of the best tested options.
- For long-horizon vibe coding, the model can overcomplicate work and enter the context-window danger zone.
- It needs goal and loop discipline to stay useful over time.
Video evidence
NEW AI Model Tier List for Vibe Coding!
Takeaway: Use GPT 5.5 in plan mode rather than as a long-horizon coding default.
The source video says it is strong and clean, but overthinks and spends too much context on extended builds.
Open source notes
