Claude Sonnet 5: current reasoning model on Okou
A current reasoning model with Built-in access through Okou.
1M tokens · Text / Vision / Code · Prompt cache
A current reasoning model from Anthropic, available in Okou's public model catalog.
What is Claude Sonnet 5?
Released June 30, 2026
Okou currently offers Claude Sonnet 5 in its public reasoning model catalog. Select it with model ID claude-sonnet-5; its relative Built-in cost is tier $$.
What's notable about Claude Sonnet 5
Headline architecture and capability features.
Sonnet 5 keeps the 1M-token context window and up to 128K output tokens. Adaptive thinking is on by default and controlled through effort — low, medium, high, xhigh, and max — with xhigh recommended for the hardest coding and agentic tasks. A new tokenizer produces ~1.0–1.35× more tokens per text than Sonnet 4.6. High-resolution vision accepts images up to 2576px on the long edge. Assistant-message prefill is not supported; use structured outputs instead.
Specs at a glance
Claude Sonnet 5 benchmarks
Vendor-reported scores. Third-party trackers report different figures for the same benchmarks depending on dataset, context settings, and agent scaffold, so treat the headline numbers as configuration-dependent. Anthropic highlights the harder SWE-bench Pro set and the Terminal-bench jump as the signals that matter for agent builders.
Claude Sonnet 5 pricing
Relative Built-in credit cost. Actual charges depend on usage and settings; check the app for current prices.
Best agent tasks for Claude Sonnet 5
The everyday agent loop that used to need Opus
Most agent loops — reading files, editing code, driving tools, verifying output — run at near-Opus quality on Sonnet 5 for a fraction of the cost. Make it the default worker and promote only the hardest planning steps to Opus 4.8 or Fable 5.
The terminal-driven coding agent
The Terminal-bench jump to ~76% (from Sonnet 4.6's ~55%) is the headline for agent builders. Use Sonnet 5 with xhigh effort for autonomous, terminal-heavy coding where wall-clock cost matters.
Frequently asked questions
How is Sonnet 5's thinking different from Sonnet 4.6?
Adaptive thinking is on by default — omitting the thinking field now runs adaptive, where Sonnet 4.6 ran thinking-off. Manual budget_tokens is removed; control depth with the effort parameter. Sonnet 5 is also the first Sonnet with the xhigh effort level.
Why did my token counts go up after switching to Sonnet 5?
Sonnet 5 uses a new tokenizer that produces roughly 1.0–1.35× more tokens for the same text than Sonnet 4.6. The per-token rate is unchanged, but your actual per-task cost and context usage can be higher — re-measure representative prompts before reacting.
Does Sonnet 5 support high-resolution images?
Yes. Sonnet 5 is the first Sonnet-tier model with high-resolution vision, accepting images up to 2576 pixels on the long edge — useful for screenshots, charts, and document understanding.
Using Claude Sonnet 5 on Okou
Choose Claude Sonnet 5 in the chat model selector when it is enabled for your workspace. Available provider connections and billing are shown in model settings.
Credits and the $$ price tier
Relative Built-in credit cost. Actual charges depend on usage and settings; check the app for current prices.
Available on Okou since June 30, 2026.
