file-modify-skill

File Modify Tool

Write new files or edit existing files with exact string replacement. Uses the workspace-contained native filesystem backend.

Path sandbox: all paths resolve inside the per-workflow workspace root. Use workspace-relative paths (e.g. reports/summary.md); .. and ~ segments are rejected, and absolute paths are remapped into the workspace.

file_modify Tool

Schema Fields

Field	Type	Required	Description
operation	string	Yes	write (create or wholesale-replace the file) or edit (surgical find-and-replace inside an existing file)
file_path	string	Yes	Path to the file
content	string	If write	Full file content to write — overwrites any existing file at this path
old_string	string	If edit	Exact text to find and replace
new_string	string	If edit	Replacement text
replace_all	boolean	No	Replace all occurrences (default: false, old_string must be unique)

Examples

Write a new file:

{
  "operation": "write",
  "file_path": "/path/to/new_file.py",
  "content": "print('hello world')"
}

Edit an existing file:

{
  "operation": "edit",
  "file_path": "/path/to/file.py",
  "old_string": "def old_name():",
  "new_string": "def new_name():"
}

Replace all occurrences:

{
  "operation": "edit",
  "file_path": "/path/to/file.py",
  "old_string": "TODO",
  "new_string": "DONE",
  "replace_all": true
}

Response Format

Write:

{"operation": "write", "file_path": "/path/to/file.py"}

Edit:

{"operation": "edit", "file_path": "/path/to/file.py", "occurrences": 1}

Guidelines

1. Use write to create a new file or replace an existing file's contents wholesale. Provide the full new contents in content; any existing file at file_path is replaced.
2. Use edit for surgical string replacement inside an existing file — it is the right choice when you want to change a small portion of a file rather than rewrite the whole thing.
3. For edit: old_string must be unique in the file unless replace_all is true.
4. Prefer edit over write when changing only part of an existing file — it produces a smaller diff and is less destructive.
5. Read the file first before editing to ensure correct context.