A reasoning model for complex code fixes and detail tracking
Claude Opus 4.1 is Anthropic's model for complex programming, research analysis, and agent tasks, and claude-opus-4-1-20250805 is its date-fixed version. It enhances real-world code tasks and reasoning on top of Opus 4, making it especially suitable for work requiring cross-file understanding, constraint tracking, and precise fixes. It can also combine image understanding for multimodal analysis.
Choose an available protocol for this model. OpenAI SDK uses a Base URL ending in /v1; Anthropic SDK uses the root URL. See each guide for protocol-specific parameters, tools and response formats.
Specifications and interface features
Clarify capacity, input/output, and calling methods before selecting a model.
Version
Claude Opus 4.1, date-fixed version of 2025-08-05
Reasoning method
Native hybrid reasoning model with extended thinking capabilities
Multimodal input and output
Text and image input; text responses
Programming benchmark
Official SWE-bench Verified: 74.5%, without extended thinking
Chat endpoints
/v1/chat/completions and /aichat2/conversations
Sessions and delivery
AI Chat v2 supports managed multi-turn conversations, JSON responses, and SSE/NDJSON streaming events
Native capabilities and benchmark descriptions refer to the model itself; session storage, file reading, and tool collaboration are platform endpoint features and do not equate to the model's independent execution capabilities.
Core Capabilities
Learn what claude-opus-4-1-20250805 can bring to your work.
Cross-file understanding, focused on necessary changes
Opus 4.1's programming improvements are not limited to code generation; they also focus on multi-file refactoring and precise fixes in real projects. After providing relevant modules, errors, and behaviors that must be preserved, you can have it analyze dependencies, identify where changes are needed, and explain the impact, making it suitable for debugging and maintenance work aimed at minimal changes.
Track details in research and analysis
When faced with multiple materials, differing definitions, and complex constraints, Opus 4.1's upgrades focus on in-depth research, data analysis, and detail tracking. It can organize claims, compare conditions, and structure conclusions around the materials provided. You can require responses to distinguish direct evidence, inferences, and items to be verified, making deliverables easier to review.
Advance complex tasks with images and text
The model has visual understanding capabilities and can analyze screenshots, charts, and textual descriptions together. In AI Chat v2, it can also use file reading and authorized tools to form multi-step workflows, linking material retrieval, content understanding, and report organization; the tool execution process and final text response can be presented separately.
Applicable Scenarios
Start with specific tasks to find where the model can make an impact.
Fixing defects in large projects
Provide the error stack, involved source files, reproduction steps, and interfaces that must not be changed, and ask it to first identify the cause, then submit patch suggestions and a regression test checklist. It is suited to maintenance tasks that require cross-module verification and controlled change scope; delivered code should still enter the testing and review process before being merged.
Organizing research materials and difference reports
Provide research text, data descriptions, or readable file links submitted through AI Chat v2, and have the model compare conclusions according to unified questions, extract key conditions, and organize a comparison table. Deliverables can include summaries, evidence locations, and questions for further verification, making it suitable for the preparation stage of technology selection and topic research.
Chart and interface issue analysis
Enter dashboard screenshots, images of interface anomalies, and business context together, and ask the model to describe visible information, propose explanations, and list verification steps. It can help turn visual observations into actionable troubleshooting checklists; when precise values are involved, it is best to provide the raw data as well to avoid calculations based solely on screenshots.
How to Choose This Model
Choose based on task complexity, input materials, and expected results.
How to Decide When Upgrading from Opus 4
If existing tasks use Opus 4 and the main challenges are code debugging, multi-file refactoring, or complex reasoning, Opus 4.1 is a clear upgrade path, and Anthropic also recommends upgrading from Opus 4. When migrating, use the same task set to compare the scope of changes, constraint adherence, and test results, rather than looking only at answer length or wording.
Choose Fixed Versions and Entry Points Separately
When you need a fixed model version for evaluation or maintaining existing workflows, use claude-opus-4-1-20250805 rather than treating it as an automatically updated latest Opus. If you already have messages management logic, choose Chat Completions; if you want hosted history, file reading, and orchestration of tool tasks, choose AI Chat v2.
Get Started
Start with a small-scale task before full integration.
01
Prepare Tasks and Materials
Define the goal, required inputs, and output requirements, using real business examples as a starting point.
02
Try It in the API Playground
Open the trial page, confirm the parameters supported by this entry point, then submit a small-scale task to review the results.
03
Integrate According to the API Documentation
Keep the full model ID, use the request format specified in the documentation, and confirm billing rules on the Pricing page.
Usage Boundaries
Understand output quality and capability scope before production use.
Programming benchmark scores do not equal the success rate of fixes in real projects. The model needs relevant code, the runtime environment, and reproduction conditions, and may misjudge the cause when dependencies or test results are missing. Ask it to explain every change, and validate patches through unit tests, integration tests, and human review.
Reasoning capability does not mean that every entry point enables extended thinking in the same way, nor does it mean the full chain of thought must be returned. When designing applications, evaluate final answers, supporting evidence, and verification steps, rather than relying on hidden reasoning content as business data.
Vision understanding is for analyzing images, not generating them; tool collaboration also does not mean the model automatically receives repository write access or code execution permissions. File and tool tasks require accessible materials and appropriate authorization, and actions such as publishing, modifying, or sending should retain clear permission boundaries.
Frequently Asked Questions
Answers to common questions about using claude-opus-4-1-20250805.
What version is claude-opus-4-1-20250805?
It is the date-pinned invocation ID for Claude Opus 4.1, corresponding to the version released on August 5, 2025. It is suitable for projects that need a specific version for testing and integration, and should not be confused with Opus 4, later Opus versions, or invocation names with the thinking suffix.
What are the main improvements over Opus 4?
The upgrade focuses on agentic tasks, real-world coding, and reasoning, with the release particularly highlighting multi-file code refactoring and detail tracking in research and data analysis. If a task requires precise fixes and fewer unrelated changes, you can prioritize evaluating Opus 4.1 with existing code tasks.
Can this version analyze images or PDFs?
Images can be submitted through image-and-text messages, and the model understands them in combination with textual instructions. PDFs can enter the file-reading workflow through file_url in AI Chat v2; do not treat image-and-text input in Chat Completions as a direct PDF upload method, and extracted content should be checked for files with complex layouts.
How do I invoke it and continue a multi-turn conversation?
Chat Completions uses this model ID with messages, with the application organizing the conversation history. In AI Chat v2, you can first submit model and question, save the returned id, and continue the conversation by sending the same id; stateful is enabled by default and can also be explicitly set to false.
Can Opus 4.1 automatically modify and test code?
The model can analyze code, propose patches, and participate in tool-driven programming workflows, but ordinary text requests will not obtain a runtime environment on their own. Automatic modification and testing require configuring available tools and permissions, and providing execution results; it is recommended to retain change review, test acceptance, and failure rollback mechanisms.
Model information · Updated: 2026-10-01. Please see the API and pricing sections for invocation parameters and billing rules.