Joopsnijder/fact-checker-mcp
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The Fact Checker MCP Server is a hybrid implementation combining CrewAI multi-agent system and MCP server technology for robust fact-checking.
Fact Checker MCP Server
Hybrid CrewAI + MCP implementation for fact-checking with multi-agent verification system.
Overview
This tool works as both:
- CrewAI multi-agent system for comprehensive fact-checking with multiple specialized agents
- MCP server for direct integration with Claude Desktop and other MCP clients
Installation & Development
This project uses UV for dependency management and virtual environment handling.
Setup
-
Install dependencies:
uv sync
-
Environment variables: Create a
.env
file with:OPENAI_API_KEY=your_openai_api_key SERPER_API_KEY=your_serper_api_key # Optional: for enhanced web search BRAVE_API_KEY=your_brave_api_key # Optional: for additional search provider
Usage
As MCP Server (for Claude Desktop)
Development mode:
mcp dev fact-checker.py
Production mode:
uv run python fact-checker.py --mcp
As Standalone Application
Interactive mode:
uv run python fact-checker.py --check
File input:
uv run python fact-checker.py --check input_text.txt
Pipeline usage:
echo "Your text to fact-check" | uv run python fact-checker.py --check
In Python Code
from fact_checker import run_fact_check_crew
# Analyze text for fact checking
report = run_fact_check_crew("Your text to analyze")
print(report.overall_reliability)
Help
Display usage instructions:
python fact-checker.py --help
MCP Server Tools
When running as MCP server, the following tools are available:
quick_verify(text: str)
- Fast verification of short claims (< 500 chars)deep_fact_check(text: str)
- Comprehensive multi-agent fact-checkingcheck_specific_statistic(statistic: str, context: str, year: int)
- Targeted statistic verificationget_history_summary()
- Summary of all completed fact checks
MCP Resources
history://list
- List of all fact-check reportshistory://report/{id}
- Specific fact-check report details
Features
- Multi-Provider Search: Automatic fallback between Serper, SearXNG, Brave Search, and web scraping
- Smart Usage Tracking: Monitors API usage limits and rotates between providers
- Comprehensive Analysis: Extracts and verifies claims, statistics, quotes, and facts
- Detailed Reporting: Provides confidence scores, sources, and explanations
- Memory & Caching: Built-in caching and memory management for efficiency
Code Quality
Format and lint:
uv run ruff format .
uv run ruff check . --fix
Run tests:
uv run pytest
Architecture
- fact-checker.py - Main server with CrewAI agents and MCP endpoints
- smart_search_tool.py - Multi-provider search system with automatic fallback
- pyproject.toml - UV project configuration with all dependencies
Requirements
- Python 3.10+
- OpenAI API key (required)
- Serper API key (optional, enhances search capabilities)
- Brave API key (optional, additional search provider)
Virtual Environment
The project uses UV's managed virtual environment. The previous manual .venv
setup has been replaced with proper UV project structure to resolve MCP CLI compatibility issues.