write, which replaces the whole file, edit only sends the part being changed - faster, and less likely to disturb the rest of the file, so prefer it when modifying an existing file. If oldText is empty, appends to the end of the file.
Dependencies
No extra dependencies, available by default.Parameters
By default
oldText must be unique in the file: if it occurs more than once the edit fails and asks for more surrounding context, so the wrong spot is not changed. Set replaceAll=true when every occurrence really should be replaced.
Each line returned by
read carries a line-number prefix like 12|. Those are display aids, not file content - do not include them in oldText / newText.Safety checks
A few checks run before writing, and report back in the result:- Modified elsewhere: if the file changed after the Agent last read it, the result carries a warning so another program’s changes are not silently overwritten.
- Syntax check: if the edited content is JSON / YAML / TOML and fails to parse, the write is refused and the file is left untouched - these formats are corrupt when half-written. Source files (
.py, for example) only warn, and only when this edit introduced a new syntax error. - Credential protection:
~/.cow/.env, which holds API keys, cannot be modified through this tool. Use theenv_configtool instead.
Use Cases
- Modify specific parameters in configuration files
- Fix bugs in code
- Insert content at specific positions in files