CLI

The fastmcp command-line interface

The fastmcp CLI is installed automatically with FastMCP. It’s the primary way to run, test, install, and interact with MCP servers from your terminal.

fastmcp --help

Commands at a Glance

Command	What it does
run	Run a server (local file, factory function, remote URL, or config file)
dev apps	Launch a browser-based preview UI for Prefab App tools
dev inspector	Launch a server inside the MCP Inspector for interactive testing
install	Install a server into Claude Code, Claude Desktop, Cursor, Gemini CLI, or Goose
inspect	Print a server’s tools, resources, and prompts as a summary or JSON report
list	List a server’s tools (and optionally resources and prompts)
call	Call a single tool with arguments
discover	Find MCP servers configured in your editors and tools
generate-cli	Scaffold a standalone typed CLI from a server’s tool schemas
project prepare	Pre-install dependencies into a reusable uv project
auth cimd	Create and validate CIMD documents for OAuth
version	Print version info (--copy to copy to clipboard)

Server Targets

Most commands need to know which server to talk to. You pass a “server spec” as the first argument, and FastMCP resolves the right transport automatically.

URLs connect to a running HTTP server:

fastmcp list http://localhost:8000/mcp
fastmcp call http://localhost:8000/mcp get_forecast city=London

Python files are loaded directly — no mcp.run() boilerplate needed. FastMCP finds a server instance named mcp, server, or app in the file, or you can specify one explicitly:

fastmcp list server.py
fastmcp run server.py:my_custom_server

Config files work too — both FastMCP’s own fastmcp.json format and standard MCP config files with an mcpServers key:

fastmcp run fastmcp.json
fastmcp list mcp-config.json

Stdio commands connect to any MCP server that speaks over standard I/O. Use --command instead of a positional argument:

fastmcp list --command 'npx -y @modelcontextprotocol/server-github'

Name-Based Resolution

If your servers are already configured in an editor or tool, you can refer to them by name. FastMCP scans configs from Claude Desktop, Claude Code, Cursor, Gemini CLI, and Goose:

fastmcp list weather
fastmcp call weather get_forecast city=London

When the same name appears in multiple configs, use the source:name form to be specific:

fastmcp list claude-code:my-server
fastmcp call cursor:weather get_forecast city=London

Run fastmcp discover to see what’s available on your machine.

Authentication

When targeting an HTTP URL, the CLI enables OAuth authentication by default. If the server requires it, you’ll be guided through the flow (typically opening a browser). If it doesn’t, the setup is a silent no-op.

To skip authentication entirely — useful for local development servers — pass --auth none:

fastmcp call http://localhost:8000/mcp my_tool --auth none

You can also pass a bearer token directly:

fastmcp list http://localhost:8000/mcp --auth "Bearer sk-..."

Transport Override

FastMCP defaults to Streamable HTTP for URL targets. If the server only supports Server-Sent Events (SSE), force the older transport:

fastmcp list http://localhost:8000 --transport sse