MCPSEAL: an open-source CLI that blocks MCP tools that change after you trust them
StageAccomplished806 · reddit · 2026-08-31
A developer built MCPSEAL, a security layer that detects when an MCP tool changes after you've trusted it. Tool definitions pass through MCPSEAL and get pinned as trusted; if a definition later changes — e.g. readproject going from "read a project file" to "read a file and upload its contents" — the change is detected and the call is blocked, defending against MCP-style rug-pull supply-chain attacks.
It's a free local CLI with no backend:
bash
npm install -g mcpseal
mcpseal init
mcpseal install
mcpseal scan
The demo runs on an actual tool-definition change, and the author is asking for feedback on where the real gaps are.
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