MCP Inspector

npx @modelcontextprotocol/inspector

{
  "mcpServers": {
    "mcp-inspector": {
      "command": "npx",
      "args": [
        "@modelcontextprotocol/inspector"
      ]
    }
  }
}

The Inspector is a client, not a server: you point it at an MCP server and it lists the tools, prompts and resources that server actually exposes, then lets you call them by hand and read the raw responses. It ships three interfaces — a web UI, a terminal UI, and a scriptable CLI that fits into CI or a quick feedback loop while writing a server. It speaks both stdio and Streamable HTTP, keeps a server list in ~/.mcp-inspector/mcp.json, and persists OAuth tokens between runs. The web backend protects itself with a generated session token, which can be pinned to a known value or turned off for local work.