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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, writes UTF-8 by default rather than the platform’s locale 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:

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Example

To get started with the FileWriterTool:
Code

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Arguments

The agent supplies these at runtime:
  • filename: The name of the file to write, relative to directory. May include subdirectories, which are created if they don’t exist.
  • content: The text content to write into the file.
  • directory (optional): The path to the directory where the file will be created. A relative path resolves inside the tool’s allowed directory — base_dir when set, the current working directory otherwise — and defaults to its root. If the directory does not exist, it will be created.
  • overwrite (optional): Whether to replace the file when it already exists. Accepts true/false (also yes/no, on/off, 1/0). Defaults to false, which reports an error instead of replacing existing content.
You set these when constructing the tool:
  • base_dir (optional): The directory that writes must stay inside. Defaults to the current working directory.
  • encoding (optional): Text encoding used to write the file. Defaults to utf-8.

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Allowed paths

Because both the directory and the filename are usually chosen by an LLM at runtime, writes are confined to a sandbox:
  • The resolved directory must be inside base_dir, which defaults to the current working directory.
  • The resolved file must then be inside that directory. .. segments, absolute paths, and symlinks are resolved before both checks, so they cannot be used to escape.
To let an agent write outside the working directory, point base_dir at the target tree:
Code
Previously an absolute directory could write anywhere the process had permission to. If you relied on that, set base_dir to the tree you want to allow. Setting CREWAI_TOOLS_ALLOW_UNSAFE_PATHS=true restores the old behavior, but it applies process-wide to every crewai-tools tool, including the SSRF protections on URL-fetching tools, so prefer base_dir.

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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.