What is Claude Opus 4.5
Claude Opus 4.5 is Anthropic’s newest “Opus”-class large language model (LLM) in the Claude 4.5 family, built for complex reasoning, professional software engineering, and long-running agentic workflows. Anthropic positions Opus 4.5 as a top-tier option that balances maximum capability with practical performance and a more accessible price point than prior Opus releases. The release completes the Claude 4.5 family alongside Sonnet 4.5 and Haiku 4.5.
Model family / identifier: Claude Opus 4.5 (API name noted by Anthropic as claude-opus-4-5-20251101).
Core features of Claude Opus 4.5
- Purpose / primary strengths: Professional software engineering, advanced agents, spreadsheet/financial modeling, extended multi-turn workflows, and “computer use” (interacting with GUIs, spreadsheets, browsers).
- Effort parameter: New request parameter (low / medium / high) that trades off compute/tokens for depth of reasoning. Useful for tuning latency/cost vs answer thoroughness.
- Enhanced computer use & vision: New zoom action and improved screen/UI inspection so the model can read fine UI elements and detailed visuals before taking actions.
- Thinking continuity: “Thinking block preservation” — Opus 4.5 preserves prior reasoning blocks to maintain continuity across long sessions.
Technical details of Claude Opus 4.5
Model identifier: claude-opus-4-5-20251101 (commonly referenced for API calls).
Context window & token limits: input 200,000 tokens / output 64,000 tokens
Modalities: text, code, images and document inputs supported; outputs are text (structured and unstructured). Partner integrations add features (batch predictions, function calling, prompt caching).
Benchmark performance & empirical results
Anthropic and multiple independent outlets have published/reported benchmark results and test behavior for Opus 4.5. Below are the most notable claims and figures:
- SWE-bench (software engineering benchmarks) — SWE-bench ≈ 80.9% in Anthropic’s reported evaluations. Opus 4.5 leads in 7/8 programming languages on Anthropic’s SWE-bench Multilingual tests.
- Real-world agent endurance — improved continuous agent operation and better handling of multi-step workflows and tool orchestration.
- Aider Polyglot: +10.6% improvement vs Sonnet 4.5 on complex coding tasks. Anthropic
- Terminal Bench: +15% improvement over Sonnet 4.5 in multi-step terminal/code workflows.
- Vending-Bench (long-horizon planning): 29% improvement over Sonnet 4.5 on long-horizon agentic tasks.
- Autonomous coding: Anthropic reports consistent performance through 30-minute autonomous coding sessions (versus earlier models that decayed earlier).
Typical and priority use cases
- Complex software engineering & long scripts — code generation, debugging, multi-file refactors, and autonomous coding agents.
- Autonomous agents and tool orchestration — chaining API calls, browsing, spreadsheet automation, and long multi-step workflows where state must be preserved across many turns.
- Large document synthesis & research — legal briefs, long reports, multi-chapter writing, and summarization over very large corpora thanks to extended context and compaction.
- Enterprise automation — internal tooling, data extraction from files/spreadsheets, and agents that operate business processes continuously.
Claude Opus 4.5 vs Gemini 3.0 Pro vs GPT 5.1
| Dimension | Claude Opus 4.5 (Anthropic) | Gemini 3.0 Pro (Google) | GPT 5.1 (OpenAI) |
|---|---|---|---|
| Model name | claude-opus-4-5-20251101-thinking;claude-opus-4-5-20251101 | gemini-3-pro-preview-thinking;gemini-3-pro-preview | gpt-5.1-chat-latest;gpt-5.1 |
| Primary strengths | Long-horizon agentic reliability, token efficiency, coding & multi-agent orchestration, safety focus. | Frontier reasoning, multimodal performance, top leaderboard scores (LMArena, GPQA, MathArena); broad Google integration. | Adaptive reasoning, developer ergonomics, extended prompt caching (24h), fast interactivity and coding tooling. |
| Representative pricing (input/output per 1M tokens) | $5 / $25 (Anthropic stated Opus 4.5). — enterprise preview pricing. | Reported preview tiers ≈ $2 / $12 or higher tiers (varies by region / plan). | $1.25 / $10 (OpenAI published GPT-5.1 API pricing). |
| Context / window & memory | Focus on context compaction, memory features, and efficient long sessions; tuned for multi-agent runs. | Very large context windows reported (1M tokens in preview) and multimodal inputs (text, image, audio, video). | Extended prompt caching and efficient adaptive reasoning; caching intended to reduce cost & latency for follow-ups. |
| Best fit for | Enterprise agents, long autonomous code workflows, cost-sensitive long runs, regulated environments with safety controls. | Research/benchmarks, multimodal reasoning, integrated Google ecosystem features (Search/Ads/Apps). | Interactive developer products, low-latency coding assistance, iterative workflows benefiting from prompt caching. |
How to access Claude opus 4.5 API
Step 1: Sign Up for API Key
Log in to cometapi.com. If you are not our user yet, please register first. Sign into your CometAPI console. Get the access credential API key of the interface. Click “Add Token” at the API token in the personal center, get the token key: sk-xxxxx and submit.
Step 2: Send Requests to Claude opus 4.5 API
Select the “claude-opus-4-5-20251101-thinking;claude-opus-4-5-20251101” endpoint to send the API request and set the request body. The request method and request body are obtained from our website API doc. Our website also provides Apifox test for your convenience. Replace <YOUR_API_KEY> with your actual CometAPI key from your account. base url is Anthropic Messages format and Chat format.
Insert your question or request into the content field—this is what the model will respond to . Process the API response to get the generated answer.
Step 3: Retrieve and Verify Results
Process the API response to get the generated answer. After processing, the API responds with the task status and output data.
See also Gemini 3 Pro Preview API