[Theia AI] MCP does not work after page reload in the browser

[safisa]

Bug Description:

Hi,
I have installed some MCP servers which worked as expected in my custom agent, but after reloading the page, the agent doesn't recognize the tools of the MCP server.

Steps to Reproduce:

1. define an MCP server, e.g.:

"filesystem": {
            "command": "npx",
            "args": [
                "-y",
                "@modelcontextprotocol/server-filesystem",
                "a-local-folder"
            ]
        }

2. start this MCP server
3. add a custom agent, and define one of the MCP tools in the custom agent system prompt.
4. test the agent and let it use the tool, it should work
5. reload the page
6. try step 4, it will not work

Additional Information

• Operating System: Mac
• Theia Version: Theia 1.57.1 (latest)

[sdirix]

This error makes sense as the tools are registered directly within the command, see here.

As the mcp servers run on the backend, we should add a mechanism to recover/register already managed servers. This would then resolve this ticket.