LLM Filesystem Tools

Secure filesystem access for Large Language Models with governance-first design.

Stop reinventing filesystem tools for every LLM project. llm-fs-tools provides production-ready, secure file operations that work with any LLM supporting function calling - Ollama, OpenAI, Anthropic, and more.

The Problem

You want your AI assistant to analyze code, search files, or explore directories. You have three bad options:

1. Inject everything into the prompt - Wastes tokens, hits context limits, can't scale
2. Use heavy frameworks - LangChain/LlamaIndex lock you into their ecosystem
3. Roll your own - Reinvent security, path validation, and tool schemas every time

The Solution

pip install llm-fs-tools

from llm_fs_tools import FileSystemTools, SecurityPolicy

# Define security boundaries
policy = SecurityPolicy(
    allowed_roots=["./my-project"],
    max_file_size_mb=5,
    blocked_patterns=["*.env", ".git/*"]
)

# Initialize tools
fs_tools = FileSystemTools(policy)

# Use with any LLM (Ollama example)
import ollama

response = ollama.chat(
    model='qwen2.5-coder',
    messages=[{'role': 'user', 'content': 'Analyze the codebase structure'}],
    tools=fs_tools.get_tool_definitions()  # Auto-generates schemas
)

# Execute tool calls
for tool_call in response.message.tool_calls:
    result = fs_tools.execute(
        tool_call.function.name,
        tool_call.function.arguments
    )

That's it. Your model can now safely explore filesystems.

---

Features

🔒 Security First

• Path traversal protection - Validates all paths stay within allowed roots
• Configurable boundaries - Whitelist directories, block patterns
• Automatic filtering - Excludes .env, .git, node_modules by default
• Size limits - Prevents reading massive files that blow up context

🛠️ Rich Tool Set

• get_directory_tree - Hierarchical structure with configurable depth
• read_file - Read with line numbers and range support
• search_codebase - Grep-style regex search across files
• list_directory - Fast flat listings

🎯 Zero Lock-In

• Framework-agnostic - Works with raw API calls, not just frameworks
• Provider-agnostic - Same tools work with Ollama, OpenAI, Anthropic
• Minimal dependencies - No heavy frameworks required
• Standard schemas - Uses OpenAI function calling format

🚀 Production Ready

• Comprehensive error handling - Graceful failures with detailed messages
• Type hints throughout - Full mypy compliance
• Extensive logging - Debug tool execution and security checks
• Tested - 80%+ coverage

---

Quick Examples

Ollama (Local Models)

import ollama
from llm_fs_tools import FileSystemTools, SecurityPolicy

policy = SecurityPolicy(allowed_roots=["./src"])
fs_tools = FileSystemTools(policy)

response = ollama.chat(
    model='codellama',
    messages=[{
        'role': 'user',
        'content': 'Find all database queries in this codebase'
    }],
    tools=fs_tools.get_tool_definitions()
)

# Handle tool calls in a loop
messages = [{'role': 'user', 'content': 'Find all database queries'}]
while response.message.tool_calls:
    messages.append(response.message)
    
    for tool_call in response.message.tool_calls:
        result = fs_tools.execute(
            tool_call.function.name,
            tool_call.function.arguments
        )
        messages.append({
            'role': 'tool',
            'content': json.dumps(result),
            'tool_call_id': tool_call.id
        })
    
    response = ollama.chat(model='codellama', messages=messages)

print(response.message.content)

OpenAI

from openai import OpenAI
from llm_fs_tools import FileSystemTools, SecurityPolicy

client = OpenAI()
policy = SecurityPolicy(allowed_roots=["./"])
fs_tools = FileSystemTools(policy)

response = client.chat.completions.create(
    model="gpt-4",
    messages=[{"role": "user", "content": "Summarize the README"}],
    tools=fs_tools.get_tool_definitions(format="openai")
)

# Execute tool calls
for tool_call in response.choices[0].message.tool_calls:
    result = fs_tools.execute(
        tool_call.function.name,
        json.loads(tool_call.function.arguments)
    )

Anthropic Claude

import anthropic
from llm_fs_tools import FileSystemTools, SecurityPolicy

client = anthropic.Anthropic()
policy = SecurityPolicy(allowed_roots=["./docs"])
fs_tools = FileSystemTools(policy)

response = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=4096,
    messages=[{"role": "user", "content": "What's in the docs?"}],
    tools=fs_tools.get_tool_definitions(format="anthropic")
)

# Handle tool use
for block in response.content:
    if block.type == "tool_use":
        result = fs_tools.execute(block.name, block.input)

---

Security Model

Path Validation

Every file operation validates paths through the security policy:

policy = SecurityPolicy(
    allowed_roots=[
        "/home/user/projects",
        "/home/user/documents"
    ],
    blocked_patterns=[
        "*.env",           # Environment files
        "*.key",           # Key files
        ".git/*",          # Git internals
        "node_modules/*",  # Dependencies
        "__pycache__/*"    # Python cache
    ],
    blocked_extensions=[
        ".pem",
        ".secret"
    ],
    max_file_size_mb=10
)

Validation Process:

1. Resolve symlinks and relative paths
2. Check if resolved path is within allowed_roots
3. Match against blocked_patterns and blocked_extensions
4. Verify file size is under max_file_size_mb

Security guarantees:

• ❌ No path traversal attacks (../../../etc/passwd)
• ❌ No symlink escapes
• ❌ No sensitive file access
• ✅ Explicit allowlist model

Error Handling

Security violations return structured errors, never raising exceptions to the LLM:

{
    "success": False,
    "error": "Access denied: Path outside allowed roots",
    "data": None,
    "metadata": {
        "tool": "read_file",
        "attempted_path": "/etc/passwd",
        "violation_type": "outside_allowed_roots"
    }
}

---

Tool Reference

get_directory_tree

Returns hierarchical directory structure.

Parameters:

• path (str, required) - Directory to analyze
• max_depth (int, default=3) - Maximum recursion depth
• include_hidden (bool, default=False) - Include hidden files

Example Output:

{
    "success": true,
    "data": {
        "name": "src",
        "type": "directory",
        "children": [
            {
                "name": "main.py",
                "type": "file",
                "size": 1024
            },
            {
                "name": "utils",
                "type": "directory",
                "children": [...]
            }
        ]
    }
}

read_file

Reads file content with optional line ranges.

Parameters:

• path (str, required) - File to read
• start_line (int, optional) - First line to read (1-indexed)
• end_line (int, optional) - Last line to read (inclusive)

Example:

# Read entire file
fs_tools.execute("read_file", {"path": "./main.py"})

# Read lines 10-20
fs_tools.execute("read_file", {
    "path": "./main.py",
    "start_line": 10,
    "end_line": 20
})

search_codebase

Grep-style search with regex support.

Parameters:

• pattern (str, required) - Search pattern (regex)
• path (str, required) - Directory to search
• file_pattern (str, default="*") - File glob filter
• case_sensitive (bool, default=False) - Case sensitivity
• max_results (int, default=100) - Result limit

Example:

# Find all TODO comments in Python files
fs_tools.execute("search_codebase", {
    "pattern": r"TODO:.*",
    "path": "./src",
    "file_pattern": "*.py"
})

Output:

{
    "success": true,
    "data": {
        "matches": [
            {
                "file": "./src/main.py",
                "line": 42,
                "content": "# TODO: Refactor this function",
                "match": "TODO: Refactor this function"
            }
        ],
        "total_matches": 1,
        "truncated": false
    }
}

list_directory

Fast flat directory listing.

Parameters:

• path (str, required) - Directory to list
• include_hidden (bool, default=False) - Include hidden files

---

Configuration

Basic Setup

from llm_fs_tools import FileSystemTools, SecurityPolicy

policy = SecurityPolicy(
    allowed_roots=["./project"],
)

fs_tools = FileSystemTools(policy)

Advanced Configuration

from pathlib import Path

policy = SecurityPolicy(
    # Multiple allowed directories
    allowed_roots=[
        "./src",
        "./docs",
        str(Path.home() / "projects")
    ],
    
    # File size limits
    max_file_size_mb=5,
    
    # Block sensitive patterns
    blocked_patterns=[
        "*.env",
        "*.key",
        "*.pem",
        ".git/*",
        "node_modules/*",
        "__pycache__/*",
        "*.pyc",
        ".venv/*"
    ],
    
    # Block by extension
    blocked_extensions=[
        ".secret",
        ".private"
    ],
    
    # Custom validation
    custom_validator=lambda path: not path.name.startswith("temp_")
)

fs_tools = FileSystemTools(policy)

Configuration File

# llm-fs-config.yaml
security:
  allowed_roots:
    - ./src
    - ./docs
  max_file_size_mb: 10
  blocked_patterns:
    - "*.env"
    - ".git/*"

import yaml
from llm_fs_tools import SecurityPolicy, FileSystemTools

with open("llm-fs-config.yaml") as f:
    config = yaml.safe_load(f)

policy = SecurityPolicy(**config["security"])
fs_tools = FileSystemTools(policy)

---

Architecture

Design Principles

1. Governance Over Scale - Security boundaries define capability, not model size
2. Explicit Over Implicit - Allowlists, not denylists
3. Simple Over Complex - Minimal API surface, zero magic
4. Portable Over Coupled - Works everywhere, depends on nothing

Component Overview

┌─────────────────────────────────────────┐
│           Your Application               │
│  (Ollama/OpenAI/Anthropic/etc)          │
└─────────────┬───────────────────────────┘
              │
              ├─ get_tool_definitions()
              │  (Returns JSON schemas)
              │
              └─ execute(name, args)
                 (Runs tool, returns result)
                        │
        ┌───────────────┴────────────────┐
        │      FileSystemTools            │
        │  ┌──────────────────────────┐  │
        │  │   Security Policy        │  │
        │  │  - Path validation       │  │
        │  │  - Size limits          │  │
        │  │  - Pattern blocking     │  │
        │  └──────────────────────────┘  │
        │  ┌──────────────────────────┐  │
        │  │   Tool Implementations   │  │
        │  │  - get_directory_tree    │  │
        │  │  - read_file            │  │
        │  │  - search_codebase      │  │
        │  │  - list_directory       │  │
        │  └──────────────────────────┘  │
        └─────────────────────────────────┘

---

Use Cases

AI Coding Assistants

# Let Claude explore and refactor your codebase
policy = SecurityPolicy(allowed_roots=["./src"])
fs_tools = FileSystemTools(policy)

response = claude.chat(
    messages=[{
        'role': 'user',
        'content': 'Refactor the authentication module for better testability'
    }],
    tools=fs_tools.get_tool_definitions()
)

Automated Code Reviews

# LLM reviews your PR changes
policy = SecurityPolicy(
    allowed_roots=["./"],
    blocked_patterns=["*.env", "node_modules/*"]
)

fs_tools = FileSystemTools(policy)

response = gpt4.chat(
    messages=[{
        'role': 'user',
        'content': 'Review the changes in src/ for security issues and best practices'
    }],
    tools=fs_tools.get_tool_definitions()
)

Documentation Generation

# Generate docs from codebase structure
policy = SecurityPolicy(allowed_roots=["./src", "./docs"])
fs_tools = FileSystemTools(policy)

response = ollama.chat(
    model='codellama',
    messages=[{
        'role': 'user',
        'content': 'Generate API documentation from the source files'
    }],
    tools=fs_tools.get_tool_definitions()
)

Dependency Analysis

# Find all imports and dependencies
fs_tools.execute("search_codebase", {
    "pattern": r"^import |^from .* import",
    "path": "./src",
    "file_pattern": "*.py"
})

---

Comparison

Feature	llm-filesystem-tools	LangChain	MCP Servers	Roll Your Own
Installation	pip install	pip install langchain	Server setup + client	❌ N/A
Dependencies	Minimal	50+ packages	MCP protocol	❌ You maintain
Security Model	Built-in policy engine	Manual	Per-server	❌ You build
Provider Support	All (OpenAI/Anthropic/Ollama)	LangChain models only	MCP clients only	✅ Up to you
Framework Lock-in	❌ None	✅ LangChain ecosystem	✅ MCP protocol	❌ None
Path Validation	✅ Automatic	❌ Manual	Varies	❌ You build
Learning Curve	5 minutes	Days	Hours	❌ Weeks

---

Roadmap

v0.1.0 (Current)

• ✅ Core filesystem tools
• ✅ Security policy engine
• ✅ Multi-provider schemas
• ✅ Path validation

v0.2.0 (Next)

• Caching layer for repeated reads
• File watching/change detection
• Batch operations
• Performance optimizations

v0.3.0

• Git integration tools
• Diff/patch operations
• Binary file support
• Archive handling (zip, tar)

v1.0.0

• Stable API
• Full test coverage
• Production hardening
• Performance benchmarks

---

Contributing

We welcome contributions! This project follows the governance-first philosophy: intelligence emerges from coordination, not complexity.

Development Setup

# Clone the repo
git clone https://github.com/dansasser/llm-filesystem-tools.git
cd llm-filesystem-tools

# Create virtual environment
python -m venv venv
source venv/bin/activate  # or `venv\Scripts\activate` on Windows

# Install dev dependencies
pip install -e ".[dev]"

# Run tests
pytest

# Run linting
ruff check .
mypy llm_fs_tools

Guidelines

• Security first - All PRs must maintain security guarantees
• Test coverage - New features need tests
• Type hints - Full typing required
• Documentation - Update docs for API changes

Areas for Contribution

• 🔧 New tool implementations
• 🛡️ Enhanced security features
• 📚 Documentation improvements
• 🧪 Test coverage expansion
• 🐛 Bug fixes

---

FAQ

Q: Does this work with LangChain/LlamaIndex?
A: Yes! You can wrap these tools in LangChain/LlamaIndex tool interfaces, but you don't need those frameworks to use this package.

Q: Can I use this in production?
A: Yes, but audit the security policy for your use case. The default blocked patterns are a starting point, not a complete security solution.

Q: What about write operations?
A: Currently read-only by design. Write operations may come in v0.3.0 with additional safeguards.

Q: Does this work on Windows?
A: Yes! Path handling is cross-platform using pathlib.

Q: Can I use this with streaming responses?
A: Yes! Tool calls work with both streaming and non-streaming LLM responses.

Q: What's the performance impact?
A: Minimal. Tool execution is typically <100ms. Directory trees are cached per call.

---

License

MIT License - see LICENSE for details.

---

Credits

Created by Dan Sasser as part of the SIM-ONE Framework - governance-first AI architecture.

Related Projects:

• ollama-prompt - Command-line tool using llm-filesystem-tools
• SIM-ONE - Comprehensive AI governance system

---

Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Email: Contact

---

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