Anthropic releases Claude Sonnet 4.6

Background

Claude Sonnet 4.6 was released on 17 February 2026 at $3 per million input tokens and $15 per million output tokens. ^[1] Sonnet is the middle tier of the Claude model family, between the larger Opus models and the smaller Haiku models.

What happened

Sonnet 4.6 became the default model for Free and Pro users on claude.ai and in Claude Cowork. ^[1] Free users also gained file creation, connectors, skills and compaction. ^[1]

Key details

The release offered a 1M-token context window in beta. ^[1] Anthropic reported that Claude Code users preferred Sonnet 4.6 to Sonnet 4.5 about 70% of the time, and to Opus 4.5 59% of the time. ^[1]

Code execution, memory, programmatic tool calling and tool search became generally available in the API. ^[1] Programmatic tool calling lets a developer's code call tools directly, rather than having the model request each call one at a time. ^[1]

Some of the features named in this release are worth defining. A connector links Claude to information held in another service. A skill is a set of instructions and files that Claude can load for a particular kind of task. Programmatic tool calling means that code written by a developer can call tools directly, rather than the model requesting each call in turn. Tool search lets a model find the right tool among many available ones.

Impact

These API features became generally available. ^[1]