Anthropic
Claude Opus 5.5
Announced Sep 22, 2026
Higher capability at lower operating cost
What could it do?
Anthropic introduced an Opus update for coding and professional work.
What changed?
Reported Fable 5.1 level performance on many tasks with lower typical costs than Opus 5.
Made demanding agent workflows more economical.
Where it fell short
Vendor comparisons depend on workload and effort; they are not a universal ranking.
Release facts were checked against the sources below. Performance claims belong to the developers; we have not independently tested these models.
Developer announcement or release logBenchmark results
A benchmark estimate, not a percentage or capability multiplier. Reasoning settings are not specified in this source table. Historical estimates can change in later snapshots.
Epoch AI methodology ↗Download the source snapshotChecked Oct 7, 2026 · CC BY 4.0Selected highest effort variant where available in the current table. Starred partial results are excluded. Claude fallback configurations can use other models when safeguards intervene.
Source: Artificial Analysis Intelligence Index ↗Download selected resultsChecked Oct 8, 2026One explicitly named variant per release. Scores come from the same Overall snapshot; preliminary entries and reported intervals are preserved. These are current ratings of earlier variants, not their launch day ratings.
Source: Text Arena ↗Download selected resultsChecked Oct 8, 2026