Claude 4.5 Sonnet
Anthropic's most intelligent model, leading the world in coding, computer use, and complex agentic tasks.
AnthropicCoding, computer use, and complex agentic tasks
Claude 4.5 Sonnet is a text generation model developed by Anthropic, released in September 2025. It is designed for software development, autonomous agent workflows, and direct computer interaction, supporting a 200,000-token context window. The model is trained with a knowledge cutoff of September 2025 and is available through Anthropic's API as well as Amazon Bedrock.
The model is built to handle extended, multi-step tasks — including executing commands, editing files, and running tests — with sustained coherence over long sessions. It scores 61.4% on OSWorld, a benchmark for real-world computer task completion, and ranks at the top of the SWE-bench Verified leaderboard for software engineering tasks. Claude 4.5 Sonnet integrates with tools like Claude Code, the Claude Agent SDK, and MCP servers, making it well-suited for building production AI agents and developer tooling.
What Claude 4.5 Sonnet supports
Large Context Window
Processes up to 200,000 tokens in a single request, enabling analysis of long documents, large codebases, or extended conversation histories without truncation.
Tool Use
Supports structured tool calling so the model can invoke external functions, APIs, or services as part of a response, enabling dynamic, action-oriented workflows.
MCP Integration
Compatible with Model Context Protocol (MCP) servers, allowing the model to connect to external data sources and tools through a standardized interface.
Agentic Task Execution
Designed to sustain coherent, autonomous work on complex multi-step tasks — including file editing, command execution, and test running — across extended sessions.
Computer Use
Can interact with real computer interfaces such as navigating GUIs, managing files, and running tools, scoring 61.4% on the OSWorld benchmark.
Code Generation
Generates, edits, and debugs code across complex software engineering tasks, ranking at the top of the SWE-bench Verified leaderboard for real-world coding ability.
Advanced Reasoning
Applies multi-step reasoning to problems in domains including finance, law, medicine, and STEM, with improved knowledge depth compared to earlier Claude generations.
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Get Started FreeBenchmark scores
Scores represent accuracy — the percentage of questions answered correctly on each test.
| Benchmark | What it tests | Score |
|---|---|---|
| MMLU-Pro | Expert knowledge across 14 academic disciplines | 86.0% |
| GPQA Diamond | PhD-level science questions (biology, physics, chemistry) | 72.7% |
| LiveCodeBench | Real-world coding tasks from recent competitions | 59.0% |
| HLE | Questions that challenge frontier models across many domains | 7.1% |
| SciCode | Scientific research coding and numerical methods | 42.8% |
| SWE-bench Verified | Real GitHub issues requiring multi-file code fixes | 77.2% |
| Terminal-Bench | Agentic coding and terminal command tasks | 50.0% |
| OSWorld | Autonomous computer use and desktop tasks | 61.4% |
| τ²-bench Retail | Agentic tool use in retail scenarios | 86.2% |
| τ²-bench Telecom | Agentic tool use in telecom scenarios | 98.0% |
Common questions about Claude 4.5 Sonnet
What is the context window for Claude 4.5 Sonnet?
Claude 4.5 Sonnet supports a context window of 200,000 tokens, allowing it to process large documents, long codebases, or extended conversations in a single request.
What is the training data cutoff for Claude 4.5 Sonnet?
According to the model metadata, Claude 4.5 Sonnet has a training data cutoff of September 2025.
Where can I access Claude 4.5 Sonnet via API?
Claude 4.5 Sonnet is available through Anthropic's API. The model ID is claude-4.5-sonnet. It is also available on Amazon Bedrock. API documentation and model identifiers can be found in the official API Model Reference.
Does Claude 4.5 Sonnet support tool calling and MCP?
Yes. Claude 4.5 Sonnet supports structured tool use and is compatible with Model Context Protocol (MCP) servers, enabling integration with external APIs, data sources, and developer tooling.
What tasks is Claude 4.5 Sonnet best suited for?
Based on the model metadata and benchmark results, Claude 4.5 Sonnet is designed for software development, autonomous agent workflows, and computer use tasks. It ranks at the top of SWE-bench Verified for coding and scores 61.4% on OSWorld for real-world computer interaction.
What people think about Claude 4.5 Sonnet
Community reception to Claude 4.5 Sonnet has been largely positive, with the model's launch generating significant discussion across Reddit. Users noted it reached the top position on LMArena shortly after release, and the r/singularity announcement thread drew over 1,300 upvotes and nearly 200 comments.
Some users raised questions about whether benchmark rankings matched real-world performance, and pricing relative to competing models was a recurring concern in later threads. Discussion of coding use cases and comparisons to other models were common topics in the community.
Claude 4.5 Sonnet takes #1 in LMArena, the first Anthropic model since Sonnet 3.5 to be #1
Claude 4.5 Sonnet is here
I tested GPT-5.1 Codex against Sonnet 4.5, and it's about time Anthropic bros take pricing seriously.
Claude 4.5 Sonnet: lots of hype, middling ranks. What gives?
Google Gemini 3.1 Pro Preview Soon?
Documentation & links
Parameters & options
When enabled, the model will explain its thought process step-by-step before providing a final answer. This can help users understand how the model arrived at its conclusions, but may result in longer responses.
You can allocate a larger thinking budget to support more thorough reasoning. Must be less than max. response size
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