filesystem

Filesystem

All file and directory operations use Claude Code's built-in tools. No MCP server needed — native tools are faster, more capable, and cost zero context tokens when idle.

Quick Reference

Filesystem MCP Tool	Replacement	Notes
read_file(path)	Read tool	Supports line offset and limit
read_multiple_files(paths)	Multiple parallel Read calls	Faster than sequential MCP calls
write_file(path, content)	Write tool	Overwrites entire file
edit_file(path, edits)	Edit tool	Exact string replacement; surgical edits
list_directory(path)	Glob or Bash ls	Glob for patterns, ls for simple listing
directory_tree(path)	Bash fd or Glob **/*	fd is fastest; Glob for pattern filtering
search_files(pattern, path)	Grep tool	Full regex, file type filters, context lines
create_directory(path)	Bash mkdir -p	-p creates intermediate directories
move_file(src, dst)	Bash mv	Also handles renames
get_file_info(path)	Bash stat or Bash ls -la	Size, permissions, timestamps
list_allowed_directories	N/A	Claude Code operates in the working directory; no sandbox restrictions

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Reading Files

Read a Single File

Use the Read tool with an absolute path:

Read: /path/to/file.py

For large files, use offset and limit to read specific sections:

Read: /path/to/file.py (offset: 100, limit: 50)

This reads 50 lines starting from line 100. Use this for files with thousands of lines to avoid flooding context.

Read Multiple Files in Parallel

Issue multiple Read calls in a single response. Claude Code executes them concurrently:

Read: /path/to/file1.py
Read: /path/to/file2.py
Read: /path/to/file3.py

Parallel reads are faster than the MCP's read_multiple_files which serialized internally.

Read Images and PDFs

The Read tool handles binary formats:

• Images (PNG, JPG, SVG): displayed visually
• PDFs: extracted text; use pages: "1-5" for large documents (max 20 pages per call)

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Writing and Editing Files

Write a New File

Use the Write tool to create a file or overwrite an existing one:

Write: /path/to/new-file.py
Content: <full file content>

The Write tool requires reading the file first if it already exists. For new files, write directly.

Edit an Existing File

Use the Edit tool for surgical modifications — replace exact string matches:

Edit: /path/to/file.py
old_string: "def old_function():"
new_string: "def new_function():"

The Edit tool fails if old_string is not unique in the file. Provide enough surrounding context to make the match unique, or use replace_all: true for find-and-replace across the entire file.

Prefer Edit over Write for existing files. Edit preserves everything outside the changed region and shows a clear diff. Write replaces the entire file.

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Finding Files

By Name Pattern (Glob)

Glob: **/*.py           → all Python files recursively
Glob: src/**/*.ts       → TypeScript files under src/
Glob: *.md              → Markdown files in current directory
Glob: **/test_*.py      → test files anywhere in the tree

Results are sorted by modification time (most recent first).

By Content (Grep)

Grep: pattern="def process_data" type="py"
Grep: pattern="TODO|FIXME" glob="*.py"
Grep: pattern="class.*Controller" output_mode="content" -C=2

Grep Parameter	Purpose
pattern	Regex pattern to match
type	File type filter (py, js, ts, rust, go, etc.)
glob	Glob pattern filter (*.tsx, src/**/*.py)
output_mode	files_with_matches (default), content, count
-C, -A, -B	Context lines: around, after, before matches
-i	Case-insensitive search

Directory Listing

Simple listing:

ls -la /path/to/directory

Recursive tree with fd:

fd . /path/to/directory --type f

Tree with depth limit:

fd . /path/to/directory --type f --max-depth 2

Filter by extension:

fd -e py /path/to/directory

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File Operations

Create Directory

mkdir -p /path/to/new/directory

The -p flag creates all intermediate directories. Always verify the parent path exists first with ls.

Move / Rename

mv /path/to/source.py /path/to/destination.py

Rename a file (same directory):

mv /path/to/old-name.py /path/to/new-name.py

Move a directory:

mv /path/to/source-dir /path/to/destination-dir

Copy

cp /path/to/source.py /path/to/destination.py
cp -r /path/to/source-dir /path/to/destination-dir

Delete

rm /path/to/file.py
rm -r /path/to/directory

Always confirm with the user before deleting files or directories.

File Metadata

stat /path/to/file.py
ls -la /path/to/file.py
wc -l /path/to/file.py

Command	Returns
stat	Size, permissions, timestamps, inode
ls -la	Permissions, owner, size, modification date
wc -l	Line count
file	MIME type detection

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Common Workflows

Find and Replace Across Files

# Find all files containing the old string
Grep: pattern="old_function_name" type="py" output_mode="files_with_matches"

# Then Edit each file
Edit: /path/to/file1.py (old_string → new_string, replace_all: true)
Edit: /path/to/file2.py (old_string → new_string, replace_all: true)

Explore an Unfamiliar Codebase

1. Check project structure: fd . --type f --max-depth 2
2. Read configuration: Read: package.json or Read: pyproject.toml
3. Find entry points: Grep: pattern="def main|if __name__" type="py"
4. Read key files identified above

Find Large Files

fd --type f --exec stat -f '%z %N' {} \; | sort -rn | head -20

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Error Handling

Error	Cause	Resolution
Read: file not found	Path incorrect or file deleted	Verify with ls or Glob
Edit: old_string not unique	Multiple matches in the file	Add more surrounding context to make it unique
Edit: old_string not found	Content changed since last read	Re-read the file, then retry with current content
Write: file not read first	Attempting to overwrite without reading	Read the file first, then Write
Permission denied	Insufficient OS permissions	Check with ls -la; use chmod if appropriate
Glob: no files found	Pattern too restrictive	Broaden the pattern; check path spelling

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Limitations

• Read returns up to 2000 lines by default. Use offset/limit for larger files.
• Read truncates lines longer than 2000 characters.
• Edit requires exact string matching — whitespace and indentation must match precisely.
• Write overwrites the entire file. No append mode. To append, read first, then write the combined content.
• Glob only matches files, not directories. Use Bash ls or fd to list directories.
• PDF reading is limited to 20 pages per call. Specify page ranges for large documents.

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Calibration Rules

1. Read before Edit. Always read a file before editing it. The Edit tool enforces this.
2. Edit over Write for existing files. Edit is surgical and shows diffs. Write is a full replacement — use it only for new files or complete rewrites.
3. Glob over Bash for file search. Glob is optimized for pattern matching. Only fall back to fd or find for queries Glob cannot express (size filters, date filters).
4. Grep over Bash for content search. Grep is optimized for ripgrep-based search with proper permissions. Never use grep or rg via Bash.
5. Parallel reads for multiple files. Issue all Read calls in a single response for concurrent execution.
6. Always use absolute paths. Claude Code tools require absolute paths. Never pass relative paths to Read, Write, or Edit.