CLI - Fastmcp — ContextQMD

import { VersionBadge } from '/snippets/version-badge.mdx'

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.

bash

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:

bash

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:

bash

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:

bash

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:

bash

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:

bash

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:

bash

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:

bash

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

You can also pass a bearer token directly:

bash

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:

bash

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