Anthropic released Claude Sonnet 5, the latest Sonnet-class model. Although it’s not a frontier-model breakthrough, Sonnet 5 meaningfully upgrades performance over previous models to deliver stronger coding capabilities, better agentic performance, and more efficient token usage. You will find more ideas in anthropic’s @claude enters workplace as a slack channel.
Anthropic’s announcement emphasized agentic performance, specifically the model’s ability to carry out multi-step work with less direct human guidance. Anthropic says Sonnet 5 can make plans, use tools such as browsers and terminals, and operate autonomously at a level that recently required larger, more expensive models.
Sonnet 5 Is More Economical With Tokens
Anthropic shows that Sonnet 5 improves over 4.6 with lower-price options and higher quality. Opus 4.8 still beats Sonnet 5 for accuracy, but Anthropic says that the effort level can be adjusted to find the best balance between cost and performance. There is also an introductory price for Sonnet 5 of $2/MTok input and $10/MTok output through August 31.
Sonnet 5 Performance Benchmarks
Sonnet 5 beats Sonnet 4.6, GPT-5.5 and Gemini 3.5 Flash across a number of benchmarks.
The BrowseComp tests how well an AI agent can locate difficult to find information on the web.
BrowseComp scores:
- Claude Sonnet 5: 84.7 (single agent)
- Claude Sonnet 4.6: 76.2
- GPT-5.5: 84.4
Terminal-Bench 2.1 is a test of an AI model’s ability with coding tasks in terminal and CLI.
Terminal-Bench 2.1 scores:
- Claude Sonnet 5: 80.4
- Claude Sonnet 4.6: 67.0
- GPT-5.5: 83.4 (Codex CLI)
- Gemini 3.5: Flash 76.2
SWE-bench Pro is a software engineering benchmark in which Sonnet 5 outperformed other similar LLMs.
SWE-bench Pro scores:
- Claude Sonnet 5: 63.2
- Claude Sonnet 4.6: 58.1
- GPT-5.5: 58.6
- Gemini 3.5 Flash: 55.1
FrontierCode is a benchmark for agentic coding across 150 tasks, a benchmark that Sonnet 5 significantly outperformed GPT-5.5.
The Claude Sonnet 5 System Card explains:
“Each task gives the agent a checked-out repository and a single issue description; the agent then works autonomously in a containerized environment to produce a final patch, with no human intervention and no timeout information.
Patches are graded against blocking functional criteria (primarily held-out unit tests) plus weighted rubric criteria, including model-graded checks for required test coverage and prohibited implementation patterns. Tasks were authored by maintainers of the underlying repositories and individually reviewed by Cognition researchers, with a random subset manually solved toverify fairness.”
The FrontierCode scores:
- Claude Sonnet 5: 38.8
- Claude Sonnet 4.6: 15.1
- GPT-5.5: 25.5
Sonnet 5 Is “Near-Opus Intelligence”
Anthropic does not claim that Sonnet 5 is a frontier model breakthrough, although it does say that it’s their most capable Sonnet-class model. The system card explains that it is less capable than Anthropic’s more capable Opus and Mythos models. Yet Anthropic does claim that it is “near-Opus intelligence at Sonnet pricing for coding, agents, and everyday professional work.”
Read the full announcement at Anthropic.
Featured Image by Shutterstock/jackpress