Fetter MCP Server

Fetter is a Python supply-chain security platform that helps monitor and validate Python package dependencies. It connects to the OSV (Open Source Vulnerabilities) database to provide real-time security intelligence about Python packages in your software supply chain.

Core Capabilities

Package Intelligence: Look up any Python package to see available versions, release information, and vulnerability status. Get detailed package metadata including version history and security advisories.

Vulnerability Detection: Check specific package versions against the OSV database to identify known security vulnerabilities. Receive detailed vulnerability reports including severity, affected versions, and remediation guidance.

Safe Version Discovery: Find the most recent version of any package that has no known vulnerabilities, helping you make informed decisions about package upgrades while maintaining security.

Domain Model

The service operates on Python packages identified by name and optional version specifiers (e.g., requests==2.31.0). Vulnerability data comes from the OSV database, which aggregates security advisories from multiple sources including PyPI, GitHub Security Advisories, and CVE databases.

Key Usage Patterns

Always use exact version specifiers when checking for vulnerabilities (e.g., requests==2.31.0 not requests>=2.0). The service requires precise version matching for accurate vulnerability assessment.

When seeking safe package versions, the service returns the latest available version with no known vulnerabilities, which may not always be the absolute latest version if recent releases have security issues.