Anthropic released Claude Opus 5.5 on 22 September 2026. It is the top model in the Claude 5.5 family and the one Anthropic points to for hard agentic work: long multi-step tasks, coding, using a computer, and knowledge work. This article covers what is confirmed, what is Anthropic's own claim, and how to decide whether your business needs it.
What Anthropic has said
On its launch page, Anthropic says Opus 5.5 performs at the level of Claude Fable 5.1 on most work and costs 40% less to run than Opus 5. Anthropic also says it leads on agentic coding, computer use and knowledge work in its own benchmarks. Treat those performance claims as the vendor's numbers. They are a good starting point, not a replacement for testing on your own tasks.
Price
The listed API price is $4 per million input tokens and $20 per million output tokens. Reading from the prompt cache costs $0.20 per million tokens, and writing to the cache costs $5. A faster mode is listed at $8 and $40. The API model ID is claude-opus-5-5.
A token is roughly three quarters of a word, so a million input tokens is about 750,000 words. For most small business workflows the model bill is small next to the cost of building and maintaining the agent. It becomes large when an agent loops many times per task or reads very long documents.
When Opus 5.5 is the right choice
- Hard reasoning across many steps: investigating a contract, reconciling several data sources, or planning a multi-stage project.
- Agentic coding and maintenance: an agent that reads a codebase, makes changes and runs tests.
- Computer use: an agent that operates software through a screen where no API exists.
- High-stakes drafting: where a wrong answer costs more than the extra model fee.
When it is not
If the job is answering common customer questions, sorting email, extracting fields from invoices or summarising meetings, a smaller model is usually enough and much cheaper. The practical pattern in 2026 is to route work: a small model handles the routine 90 percent, and Opus 5.5 is called only when a task is hard or the small model is unsure. We cover that choice in our guide to picking between Opus, Sonnet and Haiku 5.5.
How to test it fairly
- Collect 30 to 50 real examples of the task, including the awkward ones.
- Run them through Opus 5.5 and one smaller model with the same instructions.
- Score the answers against what a good staff member would do.
- Compare the cost per task, not just the price per token.
If the smaller model scores close, use it. If Opus 5.5 is clearly better on the cases that matter, pay for it on those cases only.
Want an AI agent built around your own business, with the right model for each job? Talk to Power Digital and we will scope it with you.
