[varshar]

As per Anthropic support (for Mac and Linux respectively) -

  $ echo 'export ANTHROPIC_EFFORT="high"' >> ~/.zshrc source ~/.zshrc
  $ echo 'export ANTHROPIC_EFFORT="high"' >> ~/.bashrc source ~/.bashrc

I prefer settings.json (VSCode) -

  "claudeCode.environmentVariables": [
    { "name": "ANTHROPIC_MODEL", "value": "claude-opus-4-6" },
    { "name": "CLAUDE_CODE_EFFORT_LEVEL", "value": "high" }
  ], ...

[nnoremap]

Or the 2026 version: 'Hey Claude set your thinking level to high.'