The Claude Code app has been updated, and a new thinking depth controller has been added. Maintain a medium level for daily use, and choose High or Max for challenging problems.
However, before the effort parameter is implemented, you can use the prompt keyword to trigger deeper thinking:
Think hard / think harder (deeper thinking)
Ultrathink (deeper thinking, approximately 32K thinking tokens)
The prompt keyword only applies to the current round and automatically reverts after use.