If you're wiring MCP servers into an agent and want to check them for prompt injection, tool poisoning, or supply-chain risk before you trust them, there are now a handful of open-source options. This is a factual, no-benchmarks comparison of the three I could actually find and read the docs for: our own sentinel-scan-cli, Cisco's mcp-scanner, and what used to be Invariant Labs' mcp-scan.
One thing worth flagging up front: Invariant Labs' mcp-scan repo (github.com/invariantlabs-ai/mcp-scan) now redirects to github.com/snyk/agent-scan. The project has been absorbed into Snyk and rebranded as "Agent Scan" (package snyk-agent-scan). If you're comparing tools based on older blog posts that reference "Invariant Labs mcp-scan" as a standalone, no-account CLI, that's out of date — running it now requires a free Snyk account and an SNYK_TOKEN API key (export SNYK_TOKEN=...) before the CLI will scan anything. I'm comparing against the current Snyk Agent Scan README since that's what the repo actually ships today.
All claims below are pulled directly from each project's public README as of 2026-08-24. No invented features, no synthetic benchmarks — this is a "what does the doc actually say" comparison, not a lab test.
