Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
We see that Cursor makes the initial POST request which succeeds but then the subsequent GET request is made without Mcp-Session-Id and per the protocol, there is no case where a GET request is made without Mcp-Session-Id.
The same MCP server works as expected with Claude Code and MCP Inspector.
Steps to Reproduce
Connect to an MCP server with Streamable HTTP support.
Expected Behavior
After getting the Mcp-Session-Id value in the response of the initial POST request, it should make the GET requests with that header.
Operating System
MacOS
Current Cursor Version (Menu → About Cursor → Copy)
Version: 2.2.43 (Universal)
VSCode Version: 1.105.1
Commit: 32cfbe848b35d9eb320980195985450f244b3030
Date: 2025-12-19T06:06:44.644Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Darwin arm64 25.0.0
Does this stop you from using Cursor
No - Cursor works, but with this issue
