Use Claude Opus 5.5 in AimiChat

What is Claude Opus 5.5?

Claude Opus 5.5 is the first model in Anthropic's Claude 5.5 family. Anthropic says it performs at the level of Claude Fable 5.1 on most work, generates output more than 30% faster than Opus 5, and costs about 40% less to run on typical workloads.

The other change people notice first is the writing. Anthropic says Opus 5.5 puts the most important information up front and communicates more plainly than Opus 5, which makes long answers easier to follow and check.

Claude Opus 5.5 specs and pricing

API prices are what developers pay Anthropic directly. In AimiChat you pay a flat plan price instead and do not need your own API key. Limits per message and per day depend on your plan.

What Claude Opus 5.5 is good at

• The hardest reasoning. High-stakes analysis, strategy, and questions where a wrong answer is expensive.
• Large coding work. Multi-file changes, migrations, code review and bug hunting across a whole project.
• Knowledge work. Financial and scientific analysis, reading dense charts and diagrams, and long reports.
• Careful sourcing. OpenRouter's summary notes it is more careful than Opus 5 about only stating figures and citing sources it can back up.

When to use a different model

• Everyday questions. It is more than you need for quick answers; Claude Sonnet 5 or GPT-6 Luna respond faster and use fewer credits.
• Some biology and cybersecurity requests. Anthropic ships Opus 5.5 with extra safeguards in these areas, so some dual-use requests are declined or handled more conservatively.

Claude Opus 5.5 benchmarks

These are the maker's own published results. Different companies run different test setups, so scores are only comparable within the same table from the same source.

Prompts to try with Claude Opus 5.5

1. Act as a staff engineer reviewing this pull request: correctness first, then design, then style. Be specific about what to change.
2. Here is our quarterly data. Find the three trends that matter most, state how confident you are in each, and say what data would change your view.
3. Steelman both sides of this decision, list the assumptions each depends on, then recommend one.

How to use Claude Opus 5.5 in AimiChat

1. Open AimiChat and sign in on the Aimi Genius plan or higher (see plans).
2. Choose the Genius quality in the model menu next to the message box.
3. Send your message. You can switch quality in the same chat at any time, so you can start with a faster model and move up when a question needs more depth.

Compare Claude Opus 5.5

• Claude Opus 5.5 vs GPT-6 Sol: when GPT-6 Sol is the better pick.
• Claude Opus 5.5 vs Claude Sonnet 5: when Claude Sonnet 5 is the better pick.
• Claude Opus 5.5 vs GPT-6 Luna: when GPT-6 Luna is the better pick.

See every model in AimiChat side by side.

Claude Opus 5.5 FAQ

Which AimiChat plan includes Claude Opus 5.5?

Claude Opus 5.5 powers the Genius quality on the Aimi Genius plan ($100/month).

What changed from Claude Opus 5?

Anthropic reports large gains in agentic coding and knowledge work, output more than 30% faster, about 40% lower running cost, clearer writing, and stronger resistance to prompt injection.

How big is Claude Opus 5.5's context window?

1 million tokens, with up to 128,000 output tokens through the API. The amount you can use in a single AimiChat message depends on your plan.

Is Claude Opus 5.5 better than GPT-6 Sol?

On Anthropic's published benchmarks, Opus 5.5 leads on agentic coding and knowledge work, but it costs twice as much through the API. See the full comparison for a task-by-task view.

Sources