Chapter 13: Claude Code Built-in Tools

13.1 Tool Selection Reference

Task	Tool	Example
Find files by name/pattern	Glob	**/*.test.tsx, src/components/**/*.ts
Search within files	Grep	Function name, error message, import
Read a file in full	Read	Load a file for analysis
Write a new file	Write	Create a file from scratch
Edit an existing file precisely	Edit	Replace a specific snippet via unique text match
Run a shell command	Bash	git, npm, run tests, build

13.2 Incremental Investigation Strategy

Do not read all files at once. Build understanding incrementally:

1. Grep: find entry points (function definition, export)
2. Read: read the found files
3. Grep: find usages (import, calls)
4. Read: read consumer files
5. Repeat until you have a complete picture

13.3 Fallback: Read + Write Instead of Edit

When Edit fails due to a non-unique text match:

1. Read — load the full file content
2. Modify the content programmatically
3. Write — write the updated version

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