Install MCP Without JSON — Unyly

What writes the JSON for you

The config file never disappears — tools just write it for you. Three mechanisms exist. Deep-links (cursor://, vscode://, claude://) pass the server config straight to the client app, which writes its own file after you confirm. Desktop Extensions (.mcpb) bundle the server and its runtime into one file you drag into Claude Desktop settings. Generated one-liners (claude mcp add ...) do the registration through the client’s own CLI. Unyly picks the right mechanism per client automatically. For reference, this is what actually lands in the config:

{
  "mcpServers": {
    "<name>": {
      "command": "npx",
      "args": ["-y", "<npm-package>"],
      "env": { "<KEY>": "<value>" }
    }
  }
}

When you still need JSON

Two cases: a private/internal server that is not in any catalog, and clients with no deep-link support. Then you edit the file by hand — the per-client guides on this site give the exact path and a valid example for each. The classic mistakes are a trailing comma after the last entry, a missing closing brace, and straight quotes replaced by “smart” ones after copying from a chat — any of these makes the client silently ignore the whole file.