Anthropic has launched Claude Opus 5.5, the first model in its new Claude 5.5 series. The model is aimed at coding, AI agents and other complex tasks that require longer, multi-step work.
Anthropic says Opus 5.5 can deliver performance close to its more expensive Claude Fable 5.1 across many tasks, while costing much less to run. The company says Opus 5.5 is also about 40% cheaper to run than Claude Opus 5 on typical workloads.
The model was released on September 22, 2026, as major AI companies continue to compete on model performance, coding ability and cost.
Claude Opus 5.5 Targets Coding and AI agents
Anthropic is mainly positioning Opus 5.5 for long-running coding tasks and other knowledge work handled by AI agents. An AI agent can do more than answer a single prompt. It can break a task into several steps, use tools, review information and make changes before completing the work.
Anthropic says Claude Opus 5.5 performs strongly on its internal tests for agentic coding, computer use and knowledge work. The company also says benchmark scores do not always show the full difference between advanced models because their capabilities are becoming increasingly close.
For software developers, Opus 5.5 can be used for tasks such as working with large codebases, finding and fixing bugs, adding features and completing longer coding projects.
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Opus 5.5 Offers Lower Token Prices Than Fable 5.1
Lower pricing is one of the main features of the new model. Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens. Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens.
| Model | Input Price | Output Price |
| Claude Opus 5.5 | $4/million tokens | $20/million tokens |
| Claude Fable 5.1 | $10/million tokens | $50/million tokens |
| Claude Opus 5 | $5/million tokens | $25/million tokens |
Based on these rates, Opus 5.5 is 60% cheaper than Fable 5.1 for both input and output tokens. Anthropic also says it costs about 40% less than Opus 5 on typical workloads.
The lower price could matter for AI agents in particular. Agents often make many model calls and generate large amounts of text while completing a task, which can quickly increase operating costs.
Opus 5.5 can handle up to 1 million tokens of context
Opus 5.5 comes with a 1 million-token context window. This allows developers to give the model a large amount of information within a single workflow. The model can produce up to 128,000 output tokens and has a June 2026 knowledge cutoff.
The large context window can be useful for software development and research, where an agent may need to work with large codebases, technical documents, previous conversations or other source material.
Developers Can Adjust Opus 5.5’s Reasoning Effort
Opus 5.5 also changes how developers control its reasoning. Adaptive thinking is always enabled and cannot be switched off. Developers can instead control how much reasoning the model uses through its effort setting. Anthropic lists medium effort as the default.
This gives developers more control over the balance between reasoning depth, response time and cost. However, applications using earlier Opus models may need some changes when moving to Opus 5.5. Anthropic says the API includes changes to features such as thinking blocks and forced tool use.
Opus 5.5 Scores Higher on Several Coding Tests
Anthropic’s launch data shows Opus 5.5 performing strongly on several software-development benchmarks. On Terminal-Bench 4.0, for example, Opus 5.5 scored 66.4%, compared with 55.8% for Fable 5.1 and 52.3% for Opus 5, according to benchmark results reported around the launch.
These are vendor-reported results, so they should be viewed in the context of the specific tests and evaluation methods used. Real-world results can differ depending on the task, prompts and software environment.
Anthropic’s wider claim is that Opus 5.5 can deliver performance close to Fable 5.1 across many types of work while costing less to operate.
Anthropic Adds New Safety Measures to Opus 5.5
Anthropic has also highlighted safety work alongside the model’s new capabilities. The company says Opus 5.5 was tested externally with organizations including Frontier Design and METR. Anthropic has also added safeguards covering areas such as cybersecurity and biological research.
In its internal testing, Anthropic reported that Opus 5.5 was 85% less likely to try to break through containment barriers than Opus 5 or Mythos 5.1. This figure comes from Anthropic’s own evaluation and has not been independently established.
The company also says some high-risk requests can be sent to other models when additional safeguards are needed.
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Opus 5.5 is available on major cloud platforms
Claude Opus 5.5 is available through the Claude API, Amazon Bedrock, Google Cloud and Microsoft Foundry. Anthropic’s documentation lists the model as active and gives September 22, 2026 as its release date.
The model is also available to eligible Claude users and is being added to developer tools and coding workflows. Anthropic says Claude Sonnet 5.5 and Claude Haiku 5.5 will follow, expanding the 5.5 series beyond the Opus model.
Lower Costs Could Make Opus 5.5 More Useful for AI Agents
The launch comes as AI companies place more focus on the cost of running advanced models, alongside their performance. Lower pricing could be especially useful for developers building AI agents. These systems often make multiple model calls, use tools and work through several steps before completing a task. As usage increases, token costs can become a major part of running an agent.
Opus 5.5 combines lower pricing with a 1 million-token context window and strong performance on coding and other complex tasks. This could make it a practical option for developers who need AI agents to handle longer and more demanding workflows.
The model’s performance and cost will become clearer as developers use it in real-world applications and at larger scale.