Conencting to MCP server with SSE not working

Today was the day when, to my joy, I found MCP servers in Cursor settings. Immediately I tried to connect different servers.
I succeeded with some, for example docker (GitHub - QuantGeekDev/docker-mcp: A docker MCP Server (modelcontextprotocol))

However, others didn’t work using command mode (stdio).

Unfortunately I haven’t found I way to view logs for those which didn’t work so I decided to download their source code and run as sse to debug in my IDE.

I used go-mcp/example/everything/main.go at main · MegaGrindStone/go-mcp · GitHub - sse server

P.S. I cannot put all the screenshots I want due to forum limitations, so I will do it in thread

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When I use MCP Inspector v0.3.0 (GitHub - modelcontextprotocol/inspector: Visual testing tool for MCP servers) from the official MCP team it works fine

But putting the same url to cursor doesn’t work :((

Also it produces 0 really usable logs from what I see in console

Cursor team, pls, look into it since using MCP servers is a function I have been waiting for a long time and really expect it to make I huge leap forward for cursor

Same here. Although the status of mcp server with stdio mode showing ‘connected’ and successfully located my tools, looks chat/composer wont call these tools.

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It works for me in agent mode with the one server it connected to succesfully

I assume this is just a test, because it agent can already run docker/docker compose commands

Well, now it is unhappy about me having 76 tools in 1 server?

I managed to load whole gitlab api there but now i cannot get ai to use it :frowning:

UPD. After deleting the mcp server with gitlab api it lets me do requests

I get issues like saying no servers, but it was connected


Mine was using "docker exec -i [container] running the MCP server

Same problem here. The SSE endpoints work w/ MCP inspector but when I point at the url in cursor I get the error ‘No tools found’ in the dev console. I’m using mcp-proxy to go between stdio and SSE if that matters.

I’m testing out this repo: GitHub - aaronsb/confluence-cloud-mcp and I’m able to query a list of confluence spaces via SSE. I’ll see if I can hunt down another client to test out and see if it works.

Is it possible that I’m getting this error because it’s pointing locally (“http://localhost:3099”) and cursor is somehow trying to connect to this through the internet and failing?

Or maybe it’s trying to check for tools at a different URL?

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Same error here. Trying with postgres via SSE which is working fine in the inspector but in cursor I just get “Failed to connect to Server”

I’m also unable to connect to an SSE MCP server.

Version:

Version: 0.45.7
VSCode Version: 1.96.2
Commit: 6ea842450e04c5537da4d83d51823fae13bb30f0
Date: 2025-01-30T18:32:32.733Z (1 day ago)
Electron: 32.2.6
Chromium: 128.0.6613.186
Node.js: 20.18.1
V8: 12.8.374.38-electron.0
OS: Darwin arm64 24.1.0

And the error in the output logs for Cursor Indexing and Retrieval:

2025-01-31 21:35:57.069 [info] [MCP] Handling ListTools action for sse server: http://[obscured]/sse
2025-01-31 21:35:57.069 [info] [MCP] Listing tools from sse server with identifier: http://[obscured]/sse
2025-01-31 21:35:57.069 [info] [MCP] Creating client for sse server: http://[obscured]/sse
2025-01-31 21:35:57.069 [error] [MCP] Failed to connect to SSE server: o.default is not a constructor
2025-01-31 21:35:57.069 [error] [MCP] Error listing tools for sse server http://[obscured]/sse: o.default is not a constructor

This seems to be fixed in Version: 0.45.8 and I can connect over sse to my localhost over sse, it finds the tools but I can’t seem to have cursor make a call to and of the tools. No errors in the dev tools. It’s almost like they aren’t being registered in cursor’s context?

I’ve tried a few prompts such as “call the XYZ tool” but I haven’t had any success.

I also asked if it had access to any tools and it replied with “I aim to be direct and honest: I don’t have access to any MCP (Model Control Protocol) tools, and I want to avoid making claims about capabilities I don’t have. I can help with general programming questions and code analysis, but I can’t directly interact with any external systems or tools.”

I’ve read the docs here: Advanced / Model Context Protocol (MCP)– Cursor but no matter what I prompt I can’t get it to call any of the tools (or, get a list of tools it can prompt).

This repo is what I’m trying out: GitHub - aaronsb/confluence-cloud-mcp

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Im having the same issues. Version 0.45.7

Ive tried SSE and stdio connections for python and typescript examples. Same outcome. No other logs, useful debug errors.

Screenshot 2025-02-02 at 9.18.49 AM

On windows, I’m having an issue where a cmd prompt opens when I start a MCP server. If I close the cmd prompt it ends the MCP server (Windows).

Hey, it’s pretty early days for MCP, both in our team and in the editor.

I’d expect to see some improvements around adding / debugging MCP servers soon!

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Things have been working great now that im on 0.45.10! Thank you

I only got “memory server” working via directly building node and running with node.

Will Cursor look at running MCP server’s in docker (e.g. run/exec running containers)?