Claude Opus 5.5
Overview
Claude Opus 5.5 is an Anthropic model released on September 22, 2026, for extended software engineering, autonomous agents, and professional knowledge work. On B.AI, use the model ID claude-opus-5.5. It combines a 1M-token context window with always-on adaptive thinking.
Key Features
- Agentic Coding: Designed for repository-scale engineering, iterative testing, and long-running tool workflows.
- Adjustable Reasoning: Supports
low,medium,high,xhigh, andmaxeffort. The default ismedium; adaptive thinking cannot be disabled. - Large Working Context: Supports 1M tokens of context and up to 128K output tokens, with no long-context price premium.
- Tools and Structured Results: Supports automatic tool selection, strict schemas, structured outputs, computer and browser use, and mid-conversation system messages.
- Vision and Professional Writing: Supports charts, diagrams, screenshots, documents, code explanations, and business deliverables.
Best Use Cases
- Repository-Scale Engineering: Migrations, debugging, and code review requiring sustained context and tool use.
- Business Agents: Multi-step application workflows requiring context retention and subtask coordination.
- Document Analysis: Reviewing reports and spreadsheets and preparing summaries from textual and visual evidence.
- Visual Application Workflows: Interpreting screenshots or operating interfaces through computer and browser tools.
Capabilities and Limitations
| Capability | Description |
|---|---|
| Reasoning | Always-on adaptive thinking with low, medium (default), high, xhigh, and max effort. |
| Multimodal | Text and image input; text output. Supports PDF analysis and visual interpretation. |
| Context Window | 1M tokens. |
| Max Output | 128K tokens. |
| Tool Use | Client-side and server-side tools, automatic function calling, strict schemas, and structured outputs. Forced tool selection is unsupported. |
| Prompt Caching | Minimum cacheable prompt length is 512 tokens. Supports 5-minute and 1-hour cache durations. |
| Knowledge Cutoff | June 2026. |
Known Limitations
- Disabling thinking, setting manual
budget_tokens, or forcingtool_choicetoanyor a named tool returns a 400 error. - Preserved thinking is tied to its model and prior context; incompatible edits or model switches can invalidate or drop replayed blocks.
- Safeguard refusals can return HTTP 200 with
stop_reason: "refusal"; HTTP success alone does not establish task completion.
Standard Pricing
The token prices below are shown in USD per 1 million tokens; web search is billed in USD per use.
| Model | Input (USD / 1M Tokens) | 5m Cache Write (USD / 1M Tokens) | 1h Cache Write (USD / 1M Tokens) | Cache Read (USD / 1M Tokens) | Output (USD / 1M Tokens) | Web Search (USD / use) |
|---|---|---|---|---|---|---|
| Claude Opus 5.5 | $4.00 | $5.00 | $8.00 | $0.20 | $20.00 | $0.01 |
Credits settlement: B.AI converts charges at 1 USD = 1,000,000 Credits and deducts Credits from the account balance. Web search costs 10,000 Credits ($0.01) per use.
For Claude Opus 5.5, a 5-minute cache write is billed at 1.25x the input rate and a 1-hour cache write is billed at 2x. Cache reads and refreshes are billed at 0.05x the input rate. Eligible prompts must contain at least 512 tokens.
Prices shown in the documentation are B.AI standard reference prices for base billing purposes. B.AI may provide lower actual usage costs through top-up bonuses and account benefits. Specific prices, bonus Credits, and account benefits are subject to the platform display and final billing records.