llm-tools-edit

LLM plugin providing tools for editing files. Gives LLMs the ability to create, view, and modify files using three interchangeable backends.

Installation

Install this plugin in the same environment as LLM.

llm install llm-tools-edit

Backends

This plugin provides three Toolbox backends. Each provides the same five tools:

Tool	Description
view	View file contents with line numbers, or list a directory
str_replace	Replace an exact string in a file (must appear exactly once)
create	Create a new file (errors if it already exists)
insert	Insert text after a given line number
list_files	List all files

Filesystem

Edit real files on disk, scoped to a specific directory. All paths are relative to the root directory, and path traversal outside the root is blocked.

llm -T 'Filesystem("/tmp/myproject")' "Create a Python hello world app"

The path argument is the root directory. All file operations are restricted to this directory and its subdirectories.

MemoryFS

An in-memory virtual filesystem. Files exist only in memory and are discarded when the process exits. State persists across tool calls within a single conversation, so an LLM agent can create files and iteratively edit them without touching disk.

llm -T MemoryFS "Create a Flask app with two routes"

No arguments required. Paths use absolute format (e.g. /src/main.py).

SQLiteFS

Store files in a SQLite database table. The table is created automatically if it doesn't exist. State persists across sessions — you can come back later and continue editing.

llm -T 'SQLiteFS(db_path="demo.db", table_name="files")' "Create a hello world app"

Arguments:

• db_path — path to the SQLite database file
• table_name — name of the table to store files in (schema: path TEXT PRIMARY KEY, content TEXT)

Output truncation

Large files and single-line blobs (e.g. minified JS) can overwhelm a model's context window. All three backends accept optional max_lines and max_chars keyword arguments that truncate view output and append a message telling the model how to see more:

llm -T 'Filesystem("/tmp/myproject", max_lines=200, max_chars=20000)' "Fix the bug in app.py"

fs = MemoryFS(max_lines=200, max_chars=20000)
sqlfs = SQLiteFS("demo.db", "files", max_lines=200, max_chars=20000)

• max_lines — truncate after this many lines. A footer like [Showing lines 1-200 of 5,432 total. Use view_range to see more.] is appended.
• max_chars — truncate after this many characters of formatted output. Catches the degenerate case of a single 2 MB line with no newlines. A footer like [Truncated: output exceeded 20,000 character limit. ...] is appended.

Both limits are off (None) by default. When both are set, whichever triggers first takes effect — and both footers appear if both trigger. The model can always use view_range to read specific sections of a large file without hitting the limits.

Tool details

view

View a file's contents with line numbers, or list a directory's entries.

The optional view_range parameter accepts a comma-separated start and end line number (1-indexed). Use -1 for end to mean end-of-file.

Examples: view_range="1,10" shows lines 1-10, view_range="5,-1" shows line 5 to end.

str_replace

Find and replace an exact string in a file. The old_str must appear exactly once in the file — if it appears zero times or more than once, the tool raises an error. This ensures replacements are unambiguous.

create

Create a new file with the given content. Raises an error if the file already exists (to prevent accidental overwrites). For Filesystem, parent directories are created automatically if needed.

insert

Insert text after a given line number. Use insert_line=0 to insert at the beginning of the file.

Library functions

The text-editing primitives used internally by the Toolbox classes are also available as standalone functions. You can import and use these directly in your own code.

view_lines(content, view_range="", *, max_lines=None, max_chars=None)

Format a string as numbered lines. Returns each line prefixed by its 1-indexed line number and a tab.

from llm_tools_edit.lib import view_lines

view_lines("alpha\nbeta\ngamma\n")
# '1:\talpha\n2:\tbeta\n3:\tgamma'

view_lines("alpha\nbeta\ngamma\n", view_range="2,3")
# '2:\tbeta\n3:\tgamma'

view_lines("alpha\nbeta\ngamma\n", view_range="2,-1")
# '2:\tbeta\n3:\tgamma'

The view_range parameter accepts "start,end" (1-indexed). Use -1 for end to mean end-of-file.

The optional max_lines and max_chars parameters truncate output and append a descriptive footer when limits are exceeded:

content = "".join(f"line {i}\n" for i in range(10_000))

view_lines(content, max_lines=3)
# '1:\tline 0\n2:\tline 1\n3:\tline 2\n[Showing lines 1-3 of 10000 total. Use view_range to see more.]'

view_lines("x" * 1_000_000, max_chars=50)
# '1:\txxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\n[Truncated: ...]'

str_replace_content(content, path, old_str, new_str)

Replace exactly one occurrence of old_str in content. Raises ValueError if the string is not found or appears more than once, ensuring every replacement is unambiguous. The path argument is used only in error messages.

from llm_tools_edit.lib import str_replace_content

str_replace_content("hello world", "f.py", "hello", "goodbye")
# 'goodbye world'

str_replace_content("aaa\naaa", "f.py", "aaa", "bbb")
# ValueError: old_str appears 2 times in f.py; must be unique

insert_content(content, insert_line, insert_text)

Insert text after a given line number. Use insert_line=0 to insert at the beginning.

from llm_tools_edit.lib import insert_content

insert_content("line1\nline2\n", 1, "new\n")
# 'line1\nnew\nline2\n'

insert_content("line1\nline2\n", 0, "header\n")
# 'header\nline1\nline2\n'

list_dir_from_paths(paths, prefix)

Given a flat list of absolute file paths and a directory prefix, return the set of immediate children — files as bare names, subdirectories with a trailing /. Returns None if nothing matches.

from llm_tools_edit.lib import list_dir_from_paths

list_dir_from_paths(["/src/main.py", "/src/utils.py", "/README.md"], "/")
# {'README.md', 'src/'}

list_dir_from_paths(["/src/main.py", "/src/lib/helper.py"], "/src")
# {'main.py', 'lib/'}

list_dir_from_paths(["/src/main.py"], "/other")
# None

Python API

import llm
from llm_tools_edit import Filesystem, MemoryFS, SQLiteFS

model = llm.get_model("gpt-4.1-mini")

# Real filesystem — scoped to a directory
fs = Filesystem("/tmp/myproject")
result = model.chain(
    "Create a hello world Python app",
    tools=[fs],
).text()

# In-memory filesystem
memfs = MemoryFS()
result = model.chain(
    "Create a Flask app",
    tools=[memfs],
).text()

# SQLite-backed filesystem
sqlfs = SQLiteFS("demo.db", "files")
result = model.chain(
    "Create a hello world app",
    tools=[sqlfs],
).text()

For multi-turn conversations where state persists across prompts:

memfs = MemoryFS()
conversation = model.conversation(tools=[memfs])
conversation.chain("Create /app.py with a Flask hello-world app")
conversation.chain("Add a /goodbye route to the app")
conversation.chain("View the final version of /app.py")

Development

To set up this plugin locally, first checkout the code. Then create a new virtual environment:

cd llm-tools-edit
python -m venv venv
source venv/bin/activate

Now install the dependencies and test dependencies:

llm install -e '.[test]'

To run the tests:

python -m pytest