Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
When a custom MCP server reports progress during a long-running tool call via ctx.report_progress() (FastMCP / notifications/progress), the chat UI only shows “Running in” with the tool arguments as a hidden note. No progress fraction (e.g. 25/100), no progress messages, and no status updates appear until the tool finishes.
The same behavior occurs on local HTTP, local Docker, and a remote hosted instance, including against a server build that previously showed progress correctly. That suggests a Cursor client UI regression, not a server-side change.
This same issue occurred on version 3.8.11, was then fixed, but came back in the latest versions.
Steps to Reproduce
Add a streamable-HTTP MCP server in ~/.cursor/mcp.json pointing at http://127.0.0.1:8080/mcp. The MCP must have report_progress calls.
Start the server locally (direct process or Docker).
In Cursor chat (Agent mode), ask a question that triggers the long-running tool (runtime typically 5–20+ minutes).
While the tool is running, expand the tool call block in the UI.
Observe whether progress updates appear.
Repeat against a remote hosted endpoint to confirm the issue is not environment-specific.
Expected Behavior
Progress shown next to the tool name, e.g. 12/100, 45/100.
Progress messages update during execution.
Matches behavior described in Cursor MCP progress docs and in older Cursor versions where this worked.
Operating System
MacOS
Version Information
Version: 3.13.25
VS Code Extension API: 1.128.0
Commit: 31e8d61c448c7472e371505838a0fe34083dad50
Date: 2026-07-28T06:17:45.069Z
Layout: Agent Window
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.256
OS: Darwin arm64 25.5.0
Additional Information
Impact
Long-running MCP tools (multi-minute workflows) give no feedback during execution. Users only see “Running…” until completion, which is poor UX for tools that can run 10+ minutes.
Why this looks like a client regression
Local loopback reproduces it (no proxy/Ingress).
Older hosted server image shows the same UI symptom.
Tool completes successfully; only progress display is missing.
Similar reports existed for Cursor 3.8.x and were reportedly fixed — may have regressed in 3.13.x.
Does this stop you from using Cursor
No - Cursor works, but with this issue