MODEL

claude-opus-5

Memory

Automatically append previous messages to maintain multi-turn context. May increase token usage.

Tools

Function calling

Thinking process

Max tokens

Stream Response

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README

Complete guide to using claude-opus-5

Claude Opus 5 API for Thoughtful and Proactive Agentic Work

Access Claude Opus 5 API on Kie.ai to build intelligent systems that can reason, code, analyze visual content, use tools, verify results, and carry demanding software, research, and enterprise tasks from initial planning to final delivery.

1curl https://api.kie.ai/claude/v1/messages \
2  -H "Authorization: Bearer $KIE_API_KEY" \
3  -H "Content-Type: application/json" \
4  -d '{
5    "model": "claude-opus-5",
6    "max_tokens": 4096,
7    "messages": [{ "role": "user", "content": "Plan a migration from REST to gRPC for a payments service." }],
8    "thinkingFlag": false,
9    "stream": false
10  }'

Claude Opus 5 Brings Fable 5 Intelligence into Everyday Work

Claude Opus 5 is Anthropic’s advanced model for demanding reasoning, agentic coding, and enterprise knowledge work. Drawing on the frontier intelligence represented by Claude Fable 5, it brings thoughtful and proactive execution to frequent production workloads. Claude Opus 5 can plan, implement, verify, and refine complex tasks from start to finish, supporting end-to-end software development, precise code review, root-cause bug analysis, scientific research, visual document understanding, and complex office deliverables.Now available through Kie.ai, Claude Opus 5 API allows developers to adjust reasoning effort according to different requirements for intelligence, latency, and token consumption. Lower effort levels remain effective for faster everyday workloads, while higher settings provide additional depth for difficult coding, problem-solving, and long-horizon agentic tasks. It also supports long-context processing, adaptive thinking, vision input, file analysis, prompt caching, and tool-assisted execution. Refer to the latest Claude Opus 5 API documentation on Kie.ai for current parameters, context limits, supported tools, beta features, and request formats.

What Claude Opus 5 Improves Beyond Claude Opus 4.8

Thoughtful and Proactive Execution with Claude Opus 5 API

Claude Opus 5 API takes a more active role in moving complex assignments toward completion. It can plan the required steps, use available tools, inspect intermediate results, recover from unsuccessful approaches, and continue refining its work without waiting for repeated instructions. This stronger follow-through is particularly valuable for long-horizon coding, research, automation, and enterprise tasks that cannot be completed reliably in a single response.

More Performance per Task from Anthropic Claude Opus 5 API

Efficiency improves across agentic coding, computer use, multidisciplinary reasoning, and business automation. Anthropic reports that Claude Opus 5 can outperform competing models at a similar or lower cost per task, while flexible effort settings let developers allocate fewer tokens to routine workloads and reserve deeper reasoning for more difficult assignments. Supported effort levels, thinking behavior, pricing, and request parameters should be confirmed in the latest Claude Opus 5 API documentation on Kie.ai.

Novel Problem-Solving through Claude 5 Opus API

Unfamiliar problems benefit from stronger abstraction, experimentation, and adaptive reasoning. On ARC-AGI 3, Claude Opus 5 achieved a score three times higher than the next-best evaluated model, reflecting its ability to infer hidden rules and develop solutions without relying only on familiar patterns. Claude 5 Opus API is therefore suited to analytical tasks where the initial information is incomplete, ambiguous, or unlike standard training examples.

End-to-End Coding and Bug Finding in Claude Opus 5 API

Software engineering improvements extend from implementation to verification. Claude Opus 5 API can complete multi-file features, conduct repository-wide refactors, review code with high precision and recall, identify underlying causes instead of surface symptoms, and find edge cases that simpler patches may overlook. It also performs strongly on major coding evaluations, including Frontier-Bench, CursorBench, and the Artificial Analysis Coding Agent Index. Once you've evaluated Claude Opus 5 on these end-to-end engineering tasks, run the same multi-file features and repository-wide refactors through the Grok 4.6 API to compare their coding intelligence on identical workloads.

Long-Context, Visual, and Office Work with Opus 5 API

Large repositories, lengthy documents, charts, diagrams, technical drawings, spreadsheets, and presentation materials can be processed within connected workflows. Opus 5 API maintains reasoning, instruction following, and tool use across a one-million-token context window while supporting visual analysis, multi-sheet workbook creation, structured slide decks, scientific research, and coordinated subagent execution. Check the latest API documentation for current context limits, output limits, supported file formats, vision inputs, and tool availability.

More Aligned Agentic Behavior from Anthropic Claude Opus 5 API

Anthropic’s automated behavioral audit identifies Claude Opus 5 as its most aligned model to date. It recorded the lowest overall rate of misaligned behavior among the evaluated recent Claude models, alongside stronger adherence to Claude’s Constitution and lower rates of deceptive or reckless actions. These improvements provide a more controlled foundation for applications that allow an AI system to use tools, modify files, or carry out multi-step decisions.

Stronger Cybersecurity Assistance with Defined Safeguards

Cybersecurity performance improves over Claude Opus 4.8, particularly when identifying vulnerabilities in source code and helping developers understand or remediate software weaknesses. However, Claude Opus 5 remains substantially behind Mythos 5 at developing exploits, and its safeguards restrict higher-risk activities such as exploit generation, penetration testing, and binary-based vulnerability scanning. Availability of fallback behavior, security classifiers, and related beta functions depends on the integration, so consult the latest Claude Opus 5 API documentation on Kie.ai for current implementation details.

Claude Opus 5 vs Claude Fable 5, Opus 4.8, and GPT-5.6 Sol Across Major Benchmarks

Claude Opus 5 demonstrates broad performance gains across terminal coding, knowledge work, novel problem-solving, agentic search, computer use, business automation, and biological reasoning. It records the leading result on several major evaluations, including Frontier-Bench v0.1, GDPval-AA v2, ARC-AGI 3, BrowseComp, OSWorld 2.0, and AutomationBench. Claude Fable 5 remains narrowly ahead on selected multidisciplinary, coding, legal, and health evaluations, while GPT-5.6 Sol leads DeepSWE v1.1 and stays closely matched on agentic search.

Evaluation Area	Benchmark	Claude Opus 5	Claude Fable 5	Claude Opus 4.8	GPT-5.6 Sol
Agentic Terminal Coding	Frontier-Bench v0.1	43.3%	33.7%	21.1%	34.4%
Knowledge Work	GDPval-AA v2	1861	1747	1593	1736
Novel Problem-Solving	ARC-AGI 3	30.2%	—	1.5%	7.8%
Agentic Search	BrowseComp	90.8%	87.4%	84.3%	90.4%
Multidisciplinary Reasoning	Humanity’s Last Exam, No Tools	56.3%	56.5%	49.8%	—
Multidisciplinary Reasoning	Humanity’s Last Exam, With Tools	64.7%	63.9%	57.9%	—
Computer Use	OSWorld 2.0	70.6%	66.1%	55.7%	62.6%
Agentic Coding	DeepSWE v1.1	68.8%	69.7%	59.0%	72.7%
Agentic Coding	FrontierCode v1.1, Main	53.4%	53.5%	46.5%	47.5%
Business Workflows	AutomationBench	26.0%	17.4%	17.0%	18.1%
Legal	Legal Agent Benchmark, Held-Out	11.7%	13.3%	10.4%	2.5%
Health	HealthBench Professional	59.8%	66.0%†	57.4%	60.5%
Biology	BioMysteryBench, Hard	49.4%	46.5%	42.4%	—
Biology	BioMysteryBench, Human-Solved	90.1%	89.0%†	88.5%	—

Bring Claude Opus 5 API into Your Application in Three Steps

Get started with our product in just a few simple steps...

1
1. Create an Account and Get Your Claude Opus 5 API Key
Sign up for Kie.ai or log in to your existing account, then generate an API key from the account dashboard. Keep the credential on a secure backend and never expose it in frontend code, public repositories, or shared files.
2
2. Select Anthropic Claude Opus 5 API and Prepare Your Request
Choose Claude Opus 5 from the available model list and structure the request with clear instructions, relevant context, expected output, and task boundaries. For complex coding or agentic work, include the complete specification, acceptance criteria, required files, and desired response format from the beginning.
3
3. Test and Integrate Claude 5 Opus API
Send a representative test request, review the output quality, and adjust supported settings to balance reasoning depth, latency, and token usage. Once the results are consistent, connect the request to your application and add error handling, response validation, retries, and usage monitoring. Refer to the latest Claude Opus 5 API documentation on Kie.ai for current model identifiers, endpoints, parameters, context limits, function schemas, tool-calling behavior, file requirements, and beta features.

Where Claude Opus 5 API Fits into Complex Real-World Work

End-to-End Software Engineering with Claude Opus 5 API

Development teams can use Claude Opus 5 API to explore unfamiliar repositories, implement multi-file features, refactor connected components, write tests, resolve integration failures, and validate the completed change. Stronger follow-through helps reduce unfinished stubs, superficial fixes, and repeated prompting across longer software tasks.

Code Review and Bug Investigation through Anthropic Claude Opus 5 API

Pull requests and large codebases can be examined for functional defects, hidden edge cases, architectural weaknesses, and incorrect assumptions. Anthropic Claude Opus 5 API can trace an issue beyond its visible symptom, investigate the underlying cause, and suggest corrections that account for related files, dependencies, and expected system behavior.

Research and Professional Analysis with Claude 5 Opus API

Reports, financial materials, scientific papers, policies, and extensive document collections can be evaluated as part of one connected assignment. Claude 5 Opus API can compare evidence, identify inconsistencies, develop structured conclusions, and transform the analysis into reports, recommendations, spreadsheets, or other decision-ready deliverables.

Long-Horizon Automation and Visual Work using Opus 5 API

Multi-stage applications can use Opus 5 API to interpret charts, PDFs, diagrams, screenshots, and technical references while coordinating research, tool use, content creation, and verification over extended tasks. It is also suited to workflows involving structured presentations, formula-driven spreadsheets, frontend visual replication, and parallel subagents working on independent parts of a larger objective.

Why Choose Kie.ai for Claude Opus 5 API Access

Works with the Anthropic SDK

Send model claude-opus-5 to POST /claude/v1/messages with Authorization: Bearer YOUR_API_KEY. Clients that send x-api-key, such as the Anthropic SDK, set it to Bearer YOUR_API_KEY, and anthropic-version is optional. Input and output token pricing is shown in the pricing section above.

Tool Calling with input_schema

Declare callable functions in tools, each with a name, a description and a JSON Schema input_schema. With stream set to true, tool calls arrive as tool_use blocks and input_json_delta fragments.

Streaming, Thinking and Output Length Controls

stream defaults to true and returns server-sent events, thinkingFlag turns thinking on, and max_tokens defaults to 4096 when left empty.

Other Claude Models on the Same Endpoint

Claude Opus 5.5, Claude Opus 4.8 and Claude Sonnet 5.5 use the same /claude/v1/messages endpoint with their own model ids, and GET https://api.kie.ai/anthropic/v1/models lists the available ids.

FAQs About Claude Opus 5 API

What Is Claude Opus 5?

Claude Opus 5 is Anthropic’s advanced model for demanding reasoning, agentic coding, and professional knowledge work. It is designed to carry complex assignments from initial planning through execution, verification, and final delivery, with particular strengths in end-to-end software engineering, code review, bug finding, visual analysis, scientific research, office deliverables, and long-horizon agentic tasks.

Is Claude Opus 5 API Available on Kie.ai?

Yes. Claude Opus 5 API is now available on Kie.ai for developers building software products, coding assistants, research tools, internal business systems, and automated workflows. After creating an account and generating an API key, developers can select the supported Claude Opus 5 model and follow the current documentation to prepare and send requests.

How Does Claude Opus 5 Improve on Claude Opus 4.8?

Claude Opus 5 brings significant gains in end-to-end coding, code review, root-cause bug analysis, novel problem-solving, computer use, business automation, scientific reasoning, and proactive task completion. It also performs more efficiently across different reasoning effort levels, allowing many workloads to achieve stronger results without automatically using the highest token and latency settings.

How Is Claude Opus 5 Different from Claude Fable 5?

Claude Opus 5 is positioned as a thoughtful and proactive model that approaches the frontier intelligence of Claude Fable 5 while remaining practical for frequent production workloads.

What Can Anthropic Claude Opus 5 API Be Used For?

Anthropic Claude Opus 5 API can support multi-file feature development, large codebase refactoring, pull request review, bug investigation, deep research, document analysis, spreadsheet creation, presentation development, visual interface replication, scientific reasoning, computer-use agents, and coordinated subagent workflows. It is particularly useful when an application must connect planning, execution, validation, and final delivery within one extended task.

How Much Context Does Claude Opus 5 Support?

Claude Opus 5 supports a one-million-token context window as its default and maximum context capacity. This allows it to work across large repositories, extensive document collections, long conversations, and multi-stage agentic sessions while maintaining instructions and relevant context. Current output limits, file sizes, supported formats, and context-handling requirements should be confirmed in the latest Claude Opus 5 API documentation on Kie.ai.

Does Claude Opus 5 API Support Function Calling, Tools, and Adjustable Reasoning?

Claude Opus 5 supports tool use, prompt caching, adaptive thinking, and configurable effort levels for balancing reasoning depth, latency, and token usage. Anthropic has also introduced features such as mid-conversation tool changes and automatic fallbacks in beta. Available function schemas, effort values, thinking controls, tool types, fallback behavior, and beta capabilities may vary by integration, so refer to the latest Claude Opus 5 API documentation on Kie.ai for current implementation details.

How Does Claude Opus 5 API Pricing Work on Kie.ai?

Claude Opus 5 API pricing on Kie.ai is based on the platform’s current usage rates, generally including the input and output tokens consumed by each request. Total cost can vary according to prompt length, generated output, reasoning effort, context usage, retries, and tool-assisted execution. Review the latest Kie.ai pricing information and Claude Opus 5 API documentation before estimating development or production expenses.

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