Claude Sonnet 4.5
Claude Sonnet 4.5 is an Anthropic model designed for reasoning, analysis, writing, and agentic workflows. Use it when output quality, instruction following, and reliability matter more than raw speed.
Newer version: Claude Sonnet 4.6
Provider
Anthropic
Model family
Anthropic Claude
LLM
Cost tier
Sonnet
Status
Legacy
Why teams choose it
Complex reasoning
Useful for workflows that require structured thinking, multi-step logic, and deeper analysis than lightweight models provide.
Long-context analysis
Helps teams summarize, compare, and extract insights from long documents without losing important nuance.
Coding and tools
Works well for code assistance, tool calling, and agent workflows where instructions must stay consistent across steps.
Cost-efficient routing
Useful as part of a routing stack where cheap models handle drafts and confirmations and this tier handles genuinely hard passages.
Tradeoffs to know
- Higher-quality tiers usually trade latency and dollars per token against smaller siblings in the same lineup.
- Regional availability, quota, and policy guardrails differ by account—verify what your region and billing tier can rely on today.
- When pricing or limits change often, treat routing metadata as versioned configuration, not one-time boilerplate.
When not to use this
- Not ideal for simple tasks where cheaper models in the same lineup are good enough.
- Avoid for latency-sensitive real-time chat when raw response speed outweighs reasoning depth.
- Confirm limits, pricing, and regional availability on the provider side before committing production workloads.
Technical specs
- Inputs
- text
- Outputs
- text
- Capabilities
- general-purpose
- License
- See provider
- Model string
claude-sonnet-4-5
Benchmarks
No benchmark data yet.
Anthropic Claude family lineup
Current models
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