Chess with an engine
loads medium
Tech. quality99
UX89
Time22 min 59 s
Cost≈ $4.00
Compare →
Claude Opus 5.5
Loads without errors4/5#12 of 26
Tech. quality94/100#12 of 26
UX88/100#8 of 26
Total cost≈ $17.86
Average time38 min 33 s#26 of 26
Total tokens970,297
API price: $4 / $20 per 1M input / output tokens · as of 06/10/2026 source ↗
What is Claude Opus 5.5 good for?
Anthropic's model for long-running agentic coding and knowledge work. Anthropic recommends it as the default choice for most workloads.
Description based on the maker · source ↗
- Maker
- Anthropic
- Released
- 22/09/2026
- Context window
- 1M tokens
- Model weights
- closed, the model is available through the API only
- Reasoning levels
- low medium high max
How did Claude Opus 5.5 do in the AI Lab tests?
- 4 of 5 outputs load without errors; 1 more ran after one fix by the same model.
- Its best technical result was on the “Chess with an engine” prompt (99/100).
- Did not work (original output): New York & Central Park map.
- It implemented the chess rules flawlessly – passing the objective perft test on all 6 positions.
- Average time per prompt 38 min 33 s#26 of 26
- Average cost per prompt ≈ $3.57#26 of 26
- Technical quality 94/100#12 of 26
- Automatic UX rating 88/100#8 of 26
Outputs
All outputs of Claude Opus 5.5 on the 5 prompts every other model got as well.
Solar System
loads medium
Tech. quality93
UX89
Time38 min 28 s
Cost≈ $2.93
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GTA-style game
loads medium
Tech. quality99
UX100
Time67 min 54 s
Cost≈ $3.95
Compare →
Monitor test
loads medium
Tech. quality97
UX97
Time14 min 00 s
Cost≈ $2.65
Compare →
New York & Central Park map
broken medium fixed version →
Tech. quality82
UX65
Time49 min 23 s
Cost≈ $4.33
Compare →
Cost = tokens priced with the API price list valid on the date shown next to the cost (prices change). ≈ = estimate (only the total token count is known), no ≈ = exact from input / output tokens. “Loads” = the page opens without errors; technical quality also checks behaviour during use – judge the quality in the viewer.