Build a documentation map

Prompt to try

/clear

Read huge_file.java

/context

Write detailed documentation about huge_file.java. Explain what it does and what all the functions do and how they connect together. Write that out to a file to docs/huge_file.txt

/clear

Read doc/huge_file.txt

/context

Check your work

Replace huge_file.java with some ugly file from your project. Look for something that 1500+ lines of code.

If you type @ and then start typing a filename, you can use TAB for autocomplete.

Expect to see 4x less context usage

Narration

Listen or continue with the transcript

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Transcript

Let's try a practical exercise to demonstrate the power of documentation in reducing context usage.

Take one of those large files in your codebase - maybe a complex service class or a central module with hundreds of lines - and let's compare two approaches. First, feed the entire file to Claude Code and ask it to explain what it does. Note how much context that consumes.

Then, take the same file and first ask Claude Code to write comprehensive documentation for it. Once you have that documentation, ask Claude to answer questions about the file using just the documentation instead of the whole source code.

You'll often see a four-times reduction in context usage. Instead of processing thousands of lines of code every time, Claude can work with a few hundred lines of well-written documentation. This is especially powerful when you need to make multiple queries about the same file - each subsequent query uses a quarter of the context.

This isn't just about saving tokens. It's about making your workflow faster and more efficient, especially on large codebases.