FactReason

Overview

FactReason is a Model Context Protocol server that helps you investigate npm and PyPI package upgrades by checking for evidence-backed breaking changes and querying APIs and components. It integrates directly into your AI assistant as a set of callable tools, letting Claude, Cursor, VS Code, and other MCP clients access dependency analysis on your behalf.

The server runs as a hosted remote endpoint at https://www.factreason.com/mcp with no authentication required and no local installation needed. Version v2.1.0 is available now under the MIT license, with full source code at factreason/factreason on GitHub.

FactReason is listed in the Development category on mcp.site and works with Claude Desktop, Claude Code, Cursor, VS Code, Windsurf, Zed, and any MCP-compatible client. If you maintain this project, claim your listing to verify ownership and keep information up to date.

Installation

Settings → Connectors → Add custom connector
Name: FactReason
URL:  https://www.factreason.com/mcp