prefer_write_tool

Block bash file creation, soft-remind for file reading

Problem

AI models often use bash commands for file operations:

File Creation

code

cat <<EOF > /tmp/my_script.py
import os
print("hello")
EOF

File Reading

code

cat config.json
head -n 10 README.md

File creation via bash bypasses tool UI/diffs/approval flow and has escaping issues. File reading via bash works but misses line numbers, formatting, and control that read_file provides.

Solution

This plugin uses two strategies:

File Creation

Hard block — raises ValueError, agent must use Write or Edit tool

File Reading

Soft reminder — command runs, system reminder appended suggesting read_file

main.py

from connectonion import Agent
from connectonion.useful_plugins import prefer_write_tool

agent = Agent(
    "assistant",
    tools=[bash, read_file, write, edit],
    plugins=[prefer_write_tool]
)

Detected Patterns

File Creation (hard blocked)

•cat <<EOF > file.py - heredoc redirection

•echo "..." > file.py - output redirection

•printf "..." > file.py - printf redirection

•cmd > ./file - output redirection to path

•cmd >> ./file - append redirection to path

•tee file.py - tee command

File Reading (soft reminder)

•cat file.txt - standalone cat (not piped)

•head file.txt - read first lines

•tail file.log - read last lines

•less file.txt - page through file

•more file.txt - page through file

Note: cat file | grep pattern (piped cat) is not detected — piping is legitimate bash usage.

What Happens

For file creation (blocked)

Bash file creation blocked.

<system-reminder>
You tried to create a file using bash. This is blocked.

Use the Write tool instead:
  Write(file_path="/path/to/file.py", content="...")

For editing existing files:
  Edit(file_path="/path/to/file.py", old_string="...", new_string="...")
</system-reminder>

For file reading (soft reminder)

[actual command output here]

<system-reminder>
You used bash to read a file. Consider using the read_file tool instead:
  read_file(file_path="/path/to/file.txt")

Why: read_file provides line numbers, proper formatting, and better control.
</system-reminder>

Result

File creation is stopped before execution. File reading runs normally with a gentle nudge toward read_file.

How It Works

The plugin exports two event handlers:

block_bash_file_creation (before_each_tool) — detects file creation patterns and raises ValueError. For file reading, sets a session flag.

remind_read_file (after_each_tool) — if the flag is set, appends a system reminder to the tool result message.

Combining with tool_approval

You can use both plugins together:

main.py

from connectonion.useful_plugins import tool_approval, prefer_write_tool

agent = Agent(
    "assistant",
    tools=[bash, read_file, write, edit],
    plugins=[prefer_write_tool, tool_approval]  # prefer_write_tool first
)

Order Matters

prefer_write_tool should come first to block file creation before tool_approval prompts for approval.

prefer_write_tool

Problem

File Creation

File Reading

Solution

File Creation

File Reading

Detected Patterns

File Creation (hard blocked)

File Reading (soft reminder)

What Happens

For file creation (blocked)

For file reading (soft reminder)

Result

How It Works

Combining with tool_approval

Order Matters

See Also

tool_approval

Permissions System

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