Claude model guides
What each model is for, what changed, and which effort setting to use in Claude Code.
Claude Opus 5.5
Anthropic's Opus for long-running agentic coding and knowledge work. Cheaper and faster than Opus 5, with thinking that's always on and a lower default effort.
1M128K$4 / $20medium
Read the guide →Claude Sonnet 5.5
The fast, affordable model of the Claude 5.5 family. Released September 28, 2026, at the same price as Sonnet 5, with a big jump in agentic coding.
1M128K$2 / $10high
Read the guide →How to set effort in Claude Code
low
Fastest, fewest tokens. Simple edits, quick questions, subagents.
medium
Everyday work. The default on Opus 5.5, and on Sonnet 5.5 in Claude Code.
high
More reasoning for multi-file changes. The default on most models.
xhigh
Complex coding and long agentic runs. Deeper than high, without the full cost of max.
max
Hard debugging and architecture decisions. Session-only in Claude Code.
Five ways to set it
/effortOpen the slider. Or /effort xhigh to set a level, /effort auto to go back to the model's default.
/modelUse the left and right arrow keys on the effort slider while picking a model.
claude --effort highOne run only. The level doesn't carry into your next session.
"effortLevel": "xhigh"In your settings file, to make it your standing default.
CLAUDE_CODE_EFFORT_LEVEL=highAs an environment variable (a level name, or auto).
A level set with /effort carries into your next session; max doesn't, unless you set it through the environment variable. If Claude skipped a file or stopped halfway, raise the effort. If it had everything and still got it wrong, try a more capable model.