MCP servers removed from extension still show up in VS Code

[DanTup]

I was testing the registerMcpServerDefinitionProvider API in my server and registered a new server. It showed up as expected in the tools list when running in the dev extension host.

I then removed the code from my extension that calls registerMcpServerDefinitionProvider and re-launched the dev extension host. The previous tools still show up (and the name of the MCP server), even though they're no longer being registered. VS Code appears to be able to launch the server and call tools, despite there being no definition in the .vscode/ folder or coming from the server.

I've tried running the MCP: Reset Cached Tools but it continues to show up.

I presume the server info was cached somewhere, but I can't figure out where. There are options to start/stop the server, but nothing to remove it.

[DanTup]

I also tested calling registerMcpServerDefinitionProvider but returning an empty set of servers, but it still continues to show up.

Edit: After some combination of registering servers with a different name, and then going back to registering with an empty set, it appears that definition has also gone away. I'm not sure why this is different to everything I tried previously though.

[connor4312]

We do cache the server and servers provided by an extension, since we don't want to have to activate the extension to determine the servers it provides. But I think you raise a point that if the extension is activated otherwise we should go ahead an call the provider and upate our server cache.

If you were to also remove the package.json contribution, then the server would be removed. Or, if you tried to start the server, we would reach out to the server definition provider to resolve it as needed and, seeing it no longer exists, remove it.

[DanTup]

We do cache the server and servers provided by an extension, since we don't want to have to activate the extension to determine the servers it provides

Ah, that makes sense - and explains what I was seeing. It was a bit intermittent so I wasn't sure if I had been hallucinating 😄

But I think you raise a point that if the extension is activated otherwise we should go ahead an call the provider and upate our server cache.

sgtm, thanks!