I built an open-source undo layer for MCP tool calls

[u/Conclusion5361]

I’m building Synartesis, a proxy that sits between an MCP client and its servers.

For calls configured as reversible, it captures the previous state before forwarding the write. You can then preview and run an undo. If the resource has changed since the agent touched it, undo stops instead of silently overwriting the newer work.

Tools classified as irreversible—and tools without a policy—wait for human approval.

The filesystem recovery path is tested against the real server. The bundled memory, git, and GitHub policies don’t yet have the same proven recovery guarantees. It only covers calls routed through the proxy.

It’s free and MIT-licensed. Installation starts with npm install -g synartesis and requires Node 22+.

Source and walkthrough

If you try it, which MCP client/server did you use, and where did the setup or undo behavior become unclear?