Cursor · MCP testing
Test your MCP app's UI in Cursor.
Cursor renders MCP apps in inline mode, inside a 649px wide × up to 800px tall frame. Your app has to look right in that envelope. MCPJam renders it locally against Cursor's real context so you see it before your users do.
npx @mcpjam/inspector@latestCursor's app envelope
Display modes
Cursor supports inline, defaulting to inline. Your app has to hold up in each one.
Viewport
Apps render in a 649px wide × up to 800px tall frame on desktop. Design and test to that box, not to your dev browser.
Media placement
No tool-result media placement in Cursor. Media returned by tools won't render in the app surface.
Theme
Cursor's context reports a dark theme. Test your app's contrast there.
Local, no tunnel
MCPJam's App Builder emulates the app locally and previews across viewports, with no ChatGPT subscription and a built-in tunnel when you need to test in a real client.
How we know
Probed: Verified by running against the client. Last reviewed 2026-07-08.
Walkthrough: Cursor
Run npx @mcpjam/inspector@latest, connect the MCP server config you already use, and select Cursor as the host. MCPJam emulates Cursor with anthropic/claude-sonnet-4.5 on desktop, so what you see is this host's behavior, not a generic client's.
Open your app in the App Builder preview: it renders in Cursor's 649px wide × up to 800px tall frame, in inline mode, with no subscription needed and a built-in tunnel when you need to test in a real client. Resize across the previews and confirm nothing clips.
Frequently asked questions
Run npx @mcpjam/inspector@latest, connect your server, and select Cursor. MCPJam emulates the host with anthropic/claude-sonnet-4.5, so you can watch the real behavior locally, free and open source.
Cursor renders apps in a 649px wide × up to 800px tall frame, supporting inline display modes. (Catalog last reviewed 2026-07-08.)
MCPJam's host-compat catalog (the same data behind caniuse.dev). Probed: Verified by running against the client. Last reviewed 2026-07-08.
See it in Cursor before your users do.
One command, your existing server config, Cursor's real behavior in the loop.
Open source · no credit card · ~2 min