Claude Opus 5.5
Anthropic’s recommended default: near the top on hard work, cheaper than the Opus it replaced.
About Claude Opus 5.5
Opus 5.5 replaced Opus 5 in September 2026 and is the model Anthropic tells most people to start with. Anthropic puts it at about 40% cheaper than its predecessor on typical work and more than 30% faster at writing its answer. On professional knowledge work it scored higher than Fable 5.1 in Anthropic’s own GDPval-AA test — 1846 against 1735 — and it reached 66.4% on Terminal-Bench 4.0.
Thinking is always on, at medium effort by default. For long coding sessions, reviewing a large codebase and business analysis it is the safe high-end choice; Fable 5.1 is only worth the extra on problems Opus cannot crack.
Where it’s strong
Long coding sessions and reviewing large codebases.
Financial analysis, reports and other professional knowledge work.
Automating multi-step business workflows.
A dependable default when you are not sure which model to use.
Where to be careful
Thinking cannot be switched off, so even a simple question carries some reasoning time and cost.
Anthropic itself cautions that benchmark leads have become a weak guide to real differences. Compare it on your own tasks.
Cybersecurity and biology requests may be refused by Anthropic’s safety filters.
Price
For scale: 1,000 requests of about 3,000 tokens in and 1,000 out cost $36.80 — a long prompt and a page of answer each. Every rate is published and stays the same from one request to the next. See every model.
Specs
claude-opus-5-5Call it
Use the OpenAI SDK you already have — point it at Roar AI and name the model. Read the docs.
from openai import OpenAI
client = OpenAI(base_url="https://api.roar-ai.com/v1", api_key="roar_live_…")
reply = client.chat.completions.create(
model="claude-opus-5-5",
messages=[{"role": "user", "content": "Summarise this contract in plain English."}],
)Compare Claude Opus 5.5
Questions
How much does Claude Opus 5.5 cost?
Input is $4.60 per 1M tokens; output is $23.00 per 1M tokens. For scale, 1,000 requests of about 3,000 tokens in and 1,000 out cost $36.80. The rate is published and does not change from one request to the next.
Can I use Claude Opus 5.5 alongside other models?
Yes. Every model on Roar AI is on the same API key and the same monthly invoice, so switching from Claude Opus 5.5 to another model is a change to one word in your code.
Is Claude Opus 5.5 open source?
No. Anthropic does not publish the weights, so it is only available through an API like this one.