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FileWriterTool

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Description

The FileWriterTool is a component of the crewai_tools package, designed to simplify the process of writing content to files with cross-platform compatibility (Windows, Linux, macOS). It is particularly useful in scenarios such as generating reports, saving logs, creating configuration files, and more. This tool handles path differences across operating systems, supports UTF-8 encoding, and automatically creates directories if they don’t exist, making it easier to organize your output reliably across different platforms.

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Installation

Install the crewai_tools package to use the FileWriterTool in your projects: 
pip install 'crewai[tools]'

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Example

To get started with the FileWriterTool:
Code
from crewai_tools import FileWriterTool

# Initialize the tool
file_writer_tool = FileWriterTool()

# Write content to a file in a specified directory
result = file_writer_tool._run('example.txt', 'This is a test content.', 'test_directory')
print(result)

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Arguments

  • filename: The name of the file you want to create or overwrite.
  • content: The content to write into the file.
  • directory (optional): The path to the directory where the file will be created. Defaults to the current directory (.). If the directory does not exist, it will be created.

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Path confinement

Because filename and directory may be supplied at runtime by an agent acting on untrusted content, FileWriterTool confines writes to an allow-listed set of root directories. The resolved target (after expanding symlinks and ..) must fall inside one of these roots or the write is rejected — a directory argument pointing outside them (e.g. ~/.ssh, /etc) no longer grants write access. The allow-list is, by default, the current working directory. You can extend it for deployments that legitimately write elsewhere:
  • CREWAI_TOOLS_ALLOWED_DIRS — one or more additional root directories, separated by the OS path separator (: on Linux/macOS, ; on Windows).
# Allow writes under /data and /workspace in addition to the cwd
export CREWAI_TOOLS_ALLOWED_DIRS="/data:/workspace"
If the process runs with its working directory set to the filesystem root (/) — common in containers started without a WORKDIR — the tool will not fall back to allow-listing the entire filesystem. Writes fail with a ValueError until you set CREWAI_TOOLS_ALLOWED_DIRS to an explicit directory. Set a WORKDIR (or the env var) in such deployments.
The CREWAI_TOOLS_ALLOW_UNSAFE_PATHS=true escape hatch disables path validation entirely. It is intended only for trusted local development and should not be set in any environment that runs agent-generated or otherwise untrusted instructions.

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Conclusion

By integrating the FileWriterTool into your crews, the agents can reliably write content to files across different operating systems. This tool is essential for tasks that require saving output data, creating structured file systems, and handling cross-platform file operations. It’s particularly recommended for Windows users who may encounter file writing issues with standard Python file operations. By adhering to the setup and usage guidelines provided, incorporating this tool into projects is straightforward and ensures consistent file writing behavior across all platforms.