MCP server not showing up in Claude Desktop? Here's the real fix
Symptom: You edited the config, restarted Claude, and the tools (the hammer/slider icon) still aren't there — or the server simply isn't listed.
Short answer
Don't suspect the server first. 90% of the time it's one of three things: you edited the wrong file, the JSON has a syntax error (a trailing comma kills the whole file silently), or you closed the window instead of fully quitting and reopening Claude. Fix those in order before anything else.
Why it happens, ranked by how often it's the real cause
1. You edited the wrong file (most common)
Claude Desktop reads exactly one file, and people routinely edit a copy, a backup, or the wrong OS path.
Fix: macOS: ~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json. If the file doesn't exist, create it — Claude won't make it for you.
2. Invalid JSON — usually a trailing comma
A single trailing comma or a smart-quote (“ instead of ") makes the entire file unparseable, and Claude fails silently — no error, the server just never appears.
Fix: Paste the whole file into a JSON validator (or VS Code — it underlines the error). The config must have one top-level "mcpServers" object and no comma after the last entry.
3. You didn't fully restart Claude
Closing the window leaves Claude running in the menu bar / tray. It only re-reads the config on a true relaunch.
Fix: Quit completely (macOS: Cmd+Q, or right-click the dock icon → Quit; Windows: quit from the system tray), then reopen.
4. The command isn't on PATH (npx/uvx not found)
GUI apps don't inherit your shell's PATH, so `npx` or `uvx` can be 'not found' even though it works in your terminal.
Fix: Use the absolute path to the runner (e.g. /opt/homebrew/bin/npx or the output of `which npx`) as the "command", or install the server's package globally.
Fix it step by step
- 1Confirm you're editing the exact file for your OS (path above) — not a duplicate.
- 2Validate the JSON. One trailing comma is enough to break everything.
- 3Fully quit Claude (not just close the window) and reopen.
- 4Look for the tools icon in the message box; click it to confirm the server's tools loaded.
- 5If still missing, check the logs: macOS ~/Library/Logs/Claude/mcp*.log — they tell you exactly why a server failed to start.
Still stuck?
If the logs show the server starting but no tools, the server itself may expose nothing until you give it credentials (an API key in the env block). Open the specific server's page here and copy the config again — a missing env var is the next most common cause.
FAQ
Where is the Claude Desktop MCP config file?
macOS: ~/Library/Application Support/Claude/claude_desktop_config.json. Windows: %APPDATA%\Claude\claude_desktop_config.json. If it doesn't exist, create it yourself — Claude won't generate it.
Why does my MCP server work in the terminal but not in Claude Desktop?
Because GUI apps don't inherit your shell PATH. `npx`/`uvx` resolve in your terminal but not inside Claude. Use the absolute path to the runner as the command, or install the package globally.
Do I have to restart Claude Desktop after editing the config?
Yes, and you must fully quit (Cmd+Q / quit from the tray), not just close the window. Claude only re-reads the config on a true relaunch.