Grep Tool - Claude Code

Grep searches the contents of files in the repo. It's how Claude finds usages, references, and matching lines without reading every file.

What it does

Grep runs a regex (or plain string) against file bodies and returns matching lines with file paths. You can scope it to a subdirectory, filter by glob, and ask for counts or file-only output. It's powered by a fast recursive search so it handles large repos comfortably.

When to use it

• Finding usages of a function, component, or constant.
• Hunting down TODO comments or error strings.
• Pre-filtering files before a multi-file edit.
• Confirming that a symbol doesn't leak beyond expected modules.

Gotchas

• Regex special characters need escaping - parens, brackets, pipes, dots.
• Grep returns bounded output. Very noisy patterns get truncated - narrow the scope.
• Results respect .gitignore by default, so node_modules stays out of the way.

Official docs: https://code.claude.com/docs/en/tools-reference.md