MCP Server Not Showing Up in Claude — How to Fix (2026)
Installed an MCP server but it never shows up in Claude Desktop or Claude Code? Nine times out of ten it is one of five things. Here is the checklist.
If your MCP server does not show up in Claude, the fix is almost always one of these five, in order of likelihood: you did not restart the app, the config JSON is invalid, the command is wrong, Node/uv is missing, or the server crashed on start.
1. Restart the client fully
Claude Desktop only reads claude_desktop_config.json on launch. Quit it completely (Cmd+Q on macOS — not just close the window) and reopen. Claude Code picks up claude mcp add immediately, but a running session may need a reload.
2. Validate the JSON
A single trailing comma or unbalanced brace makes Claude silently skip the whole file. Paste your config into any JSON validator. The config lives at ~/Library/Application Support/Claude/claude_desktop_config.json (macOS), %APPDATA%\Claude\claude_desktop_config.json (Windows).
3. Check the command runs by hand
Copy the command + args from your config and run them in a terminal. If npx -y some-mcp errors there, it will fail silently in Claude too. This surfaces missing packages fast.
4. Make sure the runtime is installed
Most servers run via npx (Node.js) or uvx (Python/uv). If neither is installed or on your PATH, the server never starts. Install Node.js LTS, or uv for Python servers.
5. Look for a crash
An MCP server that throws on startup (missing env var, bad token) disappears with no error in the UI. Check the client logs, and confirm every required environment variable is set.
The shortcut
Most of these come from hand-editing JSON. On Unyly the Install button writes a validated config for the client you pick, so steps 2–3 stop being a problem. Find your server, click Install, restart, done.