Strange Behavior: Cursor won't acknowledge MCP tools if they reference Sentry in their name

Bug Reports
1

I’m trying to figure out how to get Cursor to find my MCP tool to integrate Sentry, but I’m having some trouble.

  1. I made a new MCP server following the MCP docs very carefully. The server exposes a tool that allows Cursor to talk to Sentry. I am aware that an implementation of this already exists here but I would like to add additional tools besides just get_sentry_issue

  2. I add it to cursor, following the Cursor docs, via the “MCP servers” section of the Features section of the Cursor Settings page, and Cursor successfully recognizes that I have added it. If successfully sees a tool named get-alert-rule, which pings Sentry to get alert rules.

  3. I ask Cursor Composer Agent “Do you have access to any MCP tools?” It appears to not only not find any but also not even know what MCP is.

  4. I add a new function called “echo” in order to test whether my particular function is implemented poorly and silently failing somehow.

  5. I remove my existing server, quit cursor and re-open it, then re-add my existing server. Sentry can see this new “echo” function.

  6. A surprising revelation: now when I ask Cursor if it has access to any MCP tools, it says yes, and responds that it knows only about echo!

  7. I wonder if this means my “Sentry” function is poorly implemented and therefore silently failing somehow. So I swap the names of my “echo” and “get-alert-rule” functions. Again, I remove the MCP, restart Cursor, and re-add. I again see that Cursor successfully adds the MCP in the settings->features section

  8. An even MORE surprising part: now Cursor is able to see echo, which has the function body of my original MCP tool, but not get-alert-rule, which now has the function body of echo

Screenshot 2025-02-17 at 9.51.30 PM
Screenshot 2025-02-17 at 9.51.30 PM1182×606 59.4 KB

I am therefore forced to conclude that Cursor is unable to acknowledge MCP tools that contain a reference to Sentry in their name? Or maybe I’m doing something wrong?

Pls help

– additional context –

Happy to share more screenshots if helpful; unfortunately new users are only allowed to share one piece of media per post on Discourse forums.

See below for my cursor system information, retrieved from Cursor->About Cursor in the top menu

Version: 0.45.11
VSCode Version: 1.96.2
Commit: f5f18731406b73244e0558ee7716d77c8096d150
Date: 2025-02-07T09:43:58.555Z
Electron: 32.2.6
Chromium: 128.0.6613.186
Node.js: 20.18.1
V8: 12.8.374.38-electron.0
OS: Darwin arm64 23.4.0

I am not using a VPN

See below for a snapshot of the current devtools console, obtained from Cursor-> Help-> Toggle Developer Tools

[MCPService] Starting server initialization
workbench.desktop.main.js:1015 [MCPService] Getting servers: Array(1)0: {identifier: ‘b9b625d2-fe92-4f74-b727-691368f00a91’, type: ‘stdio’, command: ‘node /Users/henrydowling/projects/sentry-mcp/build/index.js’, url: undefined, status: undefined}length: 1[[Prototype]]: Array(0)
workbench.desktop.main.js:1015 [MCPService] Found servers on startup: Array(1)0: {identifier: ‘b9b625d2-fe92-4f74-b727-691368f00a91’, type: ‘stdio’, command: ‘node /Users/henrydowling/projects/sentry-mcp/build/index.js’, url: undefined}length: 1[[Prototype]]: Array(0)
workbench.desktop.main.js:1015 [MCPService] Creating client for server: b9b625d2-fe92-4f74-b727-691368f00a91
workbench.desktop.main.js:1015 [MCPService] Successfully created client for server: b9b625d2-fe92-4f74-b727-691368f00a91
workbench.desktop.main.js:1015 [MCPService] Getting servers: Array(1)0: {identifier: ‘b9b625d2-fe92-4f74-b727-691368f00a91’, type: ‘stdio’, command: ‘node /Users/henrydowling/projects/sentry-mcp/build/index.js’, url: undefined, status: undefined}length: 1[[Prototype]]: Array(0)
workbench.desktop.main.js:1015 [MCPService] Getting servers: Array(1)0: {identifier: ‘b9b625d2-fe92-4f74-b727-691368f00a91’, type: ‘stdio’, command: ‘node /Users/henrydowling/projects/sentry-mcp/build/index.js’, url: undefined, status: {…}}length: 1[[Prototype]]: Array(0)
workbench.desktop.main.js:1015 [MCPService] Getting servers: Array(1)0: {identifier: ‘b9b625d2-fe92-4f74-b727-691368f00a91’, type: ‘stdio’, command: ‘node /Users/henrydowling/projects/sentry-mcp/build/index.js’, url: undefined, status: {…}}length: 1[[Prototype]]: Array(0)
workbench.desktop.main.js:1015 [MCPService] Getting servers: Array(1)0: {identifier: ‘b9b625d2-fe92-4f74-b727-691368f00a91’, type: ‘stdio’, command: ‘node /Users/henrydowling/projects/sentry-mcp/build/index.js’, url: undefined, status: {…}}length: 1[[Prototype]]: Array(0)
workbench.desktop.main.js:1015 [MCPService] Getting servers: Array(1)0: {identifier: ‘b9b625d2-fe92-4f74-b727-691368f00a91’, type: ‘stdio’, command: ‘node /Users/henrydowling/projects/sentry-mcp/build/index.js’, url: undefined, status: {…}}length: 1[[Prototype]]: Array(0)
workbench.desktop.main.js:4915 Extension Host
3workbench.desktop.main.js:1037 Error checking file existence: Error: Unable to resolve filesystem provider with relative file path ‘vscode-settings:settingseditor’
(anonymous) @ workbench.desktop.main.js:1037
workbench.desktop.main.js:1015 [MCPService] Getting servers: Array(1)

Here is the Cursor MCP.log from my most recent session (happy to share more logs if needed)

2025-02-17 21:39:01.447 [info] [MCP] Handling CreateClient action for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.447 [info] [MCP] Creating client for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.447 [info] [MCP] Expanded command path: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.447 [info] [MCP] Starting new stdio process with command: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.448 [info] [MCP] Handling ListTools action for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.448 [info] [MCP] Listing tools from stdio server with identifier: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.448 [info] [MCP] Creating client for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.448 [info] [MCP] Expanded command path: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.448 [info] [MCP] Starting new stdio process with command: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.514 [info] [MCP] Successfully connected to stdio server with command: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.514 [info] [MCP] Successfully connected to stdio server with command: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.514 [info] [MCP] Another stdio client was created while connecting, using that one
2025-02-17 21:39:01.514 [info] [MCP] Connected to stdio server, fetching tools
2025-02-17 21:39:01.515 [info] [MCP] Handling ListTools action for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.515 [info] [MCP] Listing tools from stdio server with identifier: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.515 [info] [MCP] Creating client for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.515 [info] [MCP] Expanded command path: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.515 [info] [MCP] Reusing existing stdio client
2025-02-17 21:39:01.515 [info] [MCP] Connected to stdio server, fetching tools
2025-02-17 21:39:01.516 [info] [MCP] Found 2 tools: [“echo”,“get-alert-rule”]
2025-02-17 21:39:01.517 [info] [MCP] Found 2 tools: [“echo”,“get-alert-rule”]
2025-02-17 21:39:01.517 [info] [MCP] Handling ListTools action for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.517 [info] [MCP] Listing tools from stdio server with identifier: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.517 [info] [MCP] Creating client for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.517 [info] [MCP] Expanded command path: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:01.517 [info] [MCP] Reusing existing stdio client
2025-02-17 21:39:01.517 [info] [MCP] Connected to stdio server, fetching tools
2025-02-17 21:39:01.518 [info] [MCP] Found 2 tools: [“echo”,“get-alert-rule”]
2025-02-17 21:39:10.778 [info] [MCP] Handling ListTools action for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:10.778 [info] [MCP] Listing tools from stdio server with identifier: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:10.778 [info] [MCP] Creating client for stdio server: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:10.778 [info] [MCP] Expanded command path: node /Users/henrydowling/projects/sentry-mcp/build/index.js
2025-02-17 21:39:10.778 [info] [MCP] Reusing existing stdio client
2025-02-17 21:39:10.778 [info] [MCP] Connected to stdio server, fetching tools
2025-02-17 21:39:10.786 [info] [MCP] Found 2 tools: [“echo”,“get-alert-rule”]

2

Bump

3

I lost access to command mcp running locally in the middle of a session yesterday. Haven’t had it since. When I request Cursor/Sonnet to use MCP it obviously doesn’t know what I am referring to.

I’m quite sure something was changed in the system prompt yesterday and MCP tools were made unavailable. If only there was some transparency.

4

Yeah agreed, frustrating! I had a similar experience—the integration I describe above worked great when I first implemented it on Saturday but by Monday I couldn’t get Cursor to even acknowledge it exists!

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