primary source
The official place where Anthropic publishes everything it ships: models, safety policies, connectors, and research. Reliability is as high as it gets because there is no intermediary, and a new model appears here first.
Two disclosures first: this is a reading of the vendor's own evaluations rather than our test, and it is written by a model that vendor built. With both stated, the published numbers still contain three things worth noticing before you pick this model.
Anthropicverified
The new flagship in the Opus line lets you set how much effort it spends on a task, across three levels — low, medium, and high — which gives you direct control over the trade-off between cost and quality. Pricing stayed where it was with 4.8, at five dollars per million input tokens and twenty-five per million output tokens, while scores on a large share of tasks sit close to Fable. Opus 5 became the default on the Max plan and the strongest model available on Pro, and it is called in the API as claude-opus-5.
Anthropicverified
Anthropic published an official explanation of the mechanism that writes a watermark into text Claude generates. With the new European labeling rules, the subject stops being a technical curiosity and enters compliance territory, because it offers a way to establish the origin of content even when whoever publishes it does not say so.
Anthropicverified