letta-code/src/tools/descriptions/Edit.md

Edit

Performs exact string replacements in files.

Usage:

• You must use your Read tool at least once in the conversation before editing. This tool will error if you attempt an edit without reading the file. Exception: files under $MEMORY_DIR/system/ do not require a Read call first, since their contents are already provided in your system prompt.
• When editing text from Read tool output, ensure you preserve the exact indentation (tabs/spaces) as it appears AFTER the line number prefix. The line number prefix format is: spaces + line number + tab. Everything after that tab is the actual file content to match. Never include any part of the line number prefix in the old_string or new_string.
• ALWAYS prefer editing existing files in the codebase. NEVER write new files unless explicitly required.
• Only use emojis if the user explicitly requests it. Avoid adding emojis to files unless asked.
• The edit will FAIL if old_string is not unique in the file. Either provide a larger string with more surrounding context to make it unique or use replace_all to change every instance of old_string.
• Use replace_all for replacing and renaming strings across the file. This parameter is useful if you want to rename a variable for instance.