Why does my MCP server work in the terminal but not in the editor?

Almost always a PATH issue. The editor starts the server without loading your shell profile, so node or npx may not be found. Add the full absolute path to the command, or add a PATH override in the env block of the config.

How do I see what tools an MCP server exposes?

Run npx @modelcontextprotocol/inspector and connect it to your running server. It lists every tool, its input schema, and lets you call it interactively without an editor in the way.

Why does my MCP server connect but no tools appear in chat?

In VS Code, MCP tools only work in Agent mode. In Cursor, the server may be toggled off in Settings → MCP. In Windsurf, the 100-tool cap may be cutting off tools if you have many servers connected.

My server was working yesterday. What changed?

A npx -y server may have auto-updated to a version with a breaking change, or an API key in the env block expired. Pin to a specific version to avoid silent updates and confirm any API keys are still valid.

How to Debug an MCP Server

Start with the server logs — in Cursor and Windsurf, check the MCP section of Settings; in VS Code, open the Output panel on the MCP channel; in Claude Code, run claude mcp get <name>. If the server process is not starting at all, the cause is almost always invalid JSON in the config file, a missing command on PATH, or an incompatible Node version. Run the server command directly in a terminal first to see the raw error.

MCP servers fail with a red dot and no explanation. Here is the exact checklist — read the logs, validate the JSON, run the command in a terminal, and use the MCP Inspector — to connect any MCP server in under ten minutes.