Unable to get the MCP tool for the existing MCP server

Support Help
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I just added a new MCP tool for a MCP server, no matter what I do the agent just tells me the latest tool was not there. At first I thought maybe it’s my server’s issue. I tried to destroy the whole container with the volume, delete all the cache and redeploy but it still did not work.

However, I add the MCP server to the Codex and find out the latest tool is just there.

I’m not sure whether this is a bug or not, if so before you fix it, how can I delete the cache of the MCP server in the IDE or Agent level to solve this issue temporarily?

Steps to Reproduce

  • Install the MCP server (remote streamable MCP Server) via the .cursor/mcp.json
  • Add new tool to the MCP server and redeploy the server
  • Try to use the new tool
  • Cannot find the tool

Expected Behavior

Able to find the tool

Operating System

Windows 10/11

Version Information

Version: 3.15.19 (user setup)
VS Code Extension API: 1.128.0
Commit: de07bee81cefe43461ebf4f40c3d2d78d15052a0
Date: 2026-08-11T05:22:54.627Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.291
OS: Windows_NT x64 10.0.19045

Does this stop you from using Cursor

No - Cursor works, but with this issue

4

Hey, thanks for the report. This is a known issue. Cursor caches the tool list from the MCP server, and for non-stdio servers remote or streamable, HTTP, reconnecting and editing .cursor/mcp.json doesn’t always pick up new tools. Recreating the container on the server side won’t help here since the cache lives in the IDE.

The most reliable way to pick up a new tool right now is to fully restart Cursor close it completely and open it again, not just Reload Window. Looks like you rebuilt the server but didn’t restart the IDE, so please try that.

A couple of workarounds:

  • Change one of the hashed keys in mcp.json, for example add a dummy request parameter to the url like .../mcp?v=2. This forces Cursor to rebuild the client.
  • If you control the server, send notifications/tools/list_changed after changing tools. On some newer builds this is flaky, so a full restart is still the most reliable option.

We’re tracking the issue, but I can’t share an ETA for a fix yet. More context is in this thread: MCP server regression - does not reload tools, "disconnect" does nothing, ignores mcp.json changes, etc

Let me know if the full restart helped.

5

Thank you. After I restarted the Cursor, it works now