FastMCP CLI

FastMCP provides a command-line interface (CLI) that makes it easy to run, develop, and install your MCP servers. The CLI is automatically installed when you install FastMCP.

fastmcp --help

Commands Overview

Command	Purpose	Dependency Management
`run`	Run a FastMCP server directly	Uses your current environment; you are responsible for ensuring all dependencies are available
`dev`	Run a server with the MCP Inspector for testing	Creates an isolated environment; dependencies must be explicitly specified with `--with` and/or `--with-editable`
`install`	Install a server in MCP client applications	Creates an isolated environment; dependencies must be explicitly specified with `--with` and/or `--with-editable`
`inspect`	Generate a JSON report about a FastMCP server	Uses your current environment; you are responsible for ensuring all dependencies are available
`version`	Display version information	N/A

Command Details

`run`

Run a FastMCP server directly or proxy a remote server.

fastmcp run server.py

This command runs the server directly in your current Python environment. You are responsible for ensuring all dependencies are available.

Options

Option	Flag	Description
Transport	`--transport`, `-t`	Transport protocol to use (`stdio`, `http`, or `sse`)
Host	`--host`	Host to bind to when using http transport (default: 127.0.0.1)
Port	`--port`, `-p`	Port to bind to when using http transport (default: 8000)
Path	`--path`	Path to bind to when using http transport (default: `/mcp/` or `/sse/` for SSE)
Log Level	`--log-level`, `-l`	Log level (DEBUG, INFO, WARNING, ERROR, CRITICAL)
No Banner	`--no-banner`	Disable the startup banner display

Server Specification

New in version: 2.3.5 The server can be specified in three ways:

server.py - imports the module and looks for a FastMCP object named mcp, server, or app. Errors if no such object is found.
server.py:custom_name - imports and uses the specified server object
http://server-url/path or https://server-url/path - connects to a remote server and creates a proxy

When using fastmcp run with a local file, it ignores the if __name__ == "__main__" block entirely. Instead, it finds your server object and calls its run() method directly with the transport options you specify. This means you can use fastmcp run to override the transport specified in your code.

For example, if your code contains:

# server.py
from fastmcp import FastMCP

mcp = FastMCP("MyServer")

@mcp.tool
def hello(name: str) -> str:
    return f"Hello, {name}!"

if __name__ == "__main__":
    # This is ignored when using `fastmcp run`!
    mcp.run(transport="stdio")

You can run it with Streamable HTTP transport regardless of what’s in the __main__ block:

fastmcp run server.py --transport http --port 8000

Examples

# Run a local server with Streamable HTTP transport on a custom port
fastmcp run server.py --transport http --port 8000

# Connect to a remote server and proxy as a stdio server
fastmcp run https://example.com/mcp-server

# Connect to a remote server with specified log level
fastmcp run https://example.com/mcp-server --log-level DEBUG

`dev`

Run a MCP server with the MCP Inspector for testing.

fastmcp dev server.py

This command runs your server in an isolated environment. All dependencies must be explicitly specified using the --with and/or --with-editable options.

The dev command is a shortcut for testing a server over STDIO only. When the Inspector launches, you may need to:

Select “STDIO” from the transport dropdown
Connect manually

This command does not support HTTP testing. To test a server over Streamable HTTP or SSE:

Start your server manually with the appropriate transport using either the command line:
```
fastmcp run server.py --transport http
```
or by setting the transport in your code:
```
python server.py  # Assuming your __main__ block sets Streamable HTTP transport
```
Open the MCP Inspector separately and connect to your running server

Options

Option	Flag	Description
Editable Package	`--with-editable`, `-e`	Directory containing pyproject.toml to install in editable mode
Additional Packages	`--with`	Additional packages to install (can be used multiple times)
Inspector Version	`--inspector-version`	Version of the MCP Inspector to use
UI Port	`--ui-port`	Port for the MCP Inspector UI
Server Port	`--server-port`	Port for the MCP Inspector Proxy server

Example

# Run dev server with editable mode and additional packages
fastmcp dev server.py -e . --with pandas --with matplotlib

`install`

New in version: 2.10.3 Install a MCP server in MCP client applications. FastMCP currently supports the following clients:

Claude Code - Installs via Claude Code’s built-in MCP management system
Claude Desktop - Installs via direct configuration file modification
Cursor - Installs via deeplink that opens Cursor for user confirmation
MCP JSON - Generates standard MCP JSON configuration for manual use

fastmcp install claude-code server.py
fastmcp install claude-desktop server.py
fastmcp install cursor server.py
fastmcp install mcp-json server.py

Note that for security reasons, MCP clients usually run every server in a completely isolated environment. Therefore, all dependencies must be explicitly specified using the --with and/or --with-editable options (following uv conventions) or by attaching them to your server in code via the dependencies parameter. You should not assume that the MCP server will have access to your local environment.

uv must be installed and available in your system PATH. Both Claude Desktop and Cursor run in isolated environments and need uv to manage dependencies. On macOS, install uv globally with Homebrew for Claude Desktop compatibility: brew install uv.

FastMCP install commands focus on local server files with STDIO transport. For remote servers running with HTTP or SSE transport, use your client’s native configuration - FastMCP’s value is simplifying the complex local setup with dependencies and uv commands.

Server Specification

The install command supports the same file.py:object notation as the run command:

server.py - imports the module and looks for a FastMCP object named mcp, server, or app. Errors if no such object is found.
server.py:custom_name - imports and uses the specified server object

Options

Option	Flag	Description
Server Name	`--name`, `-n`	Custom name for the server (defaults to server’s name attribute or file name)
Editable Package	`--with-editable`, `-e`	Directory containing pyproject.toml to install in editable mode
Additional Packages	`--with`	Additional packages to install (can be used multiple times)
Environment Variables	`--env`	Environment variables in KEY=VALUE format (can be used multiple times)
Environment File	`--env-file`, `-f`	Load environment variables from a .env file

Examples

# Auto-detects server object (looks for 'mcp', 'server', or 'app')
fastmcp install claude-desktop server.py

# Uses specific server object
fastmcp install claude-desktop server.py:my_server

# With custom name and dependencies
fastmcp install claude-desktop server.py:my_server --name "My Analysis Server" --with pandas

# Install in Claude Code with environment variables
fastmcp install claude-code server.py --env API_KEY=secret --env DEBUG=true

# Install in Cursor with environment variables
fastmcp install cursor server.py --env API_KEY=secret --env DEBUG=true

# Install with environment file
fastmcp install cursor server.py --env-file .env

# Generate MCP JSON configuration
fastmcp install mcp-json server.py --name "My Server" --with pandas

# Copy JSON configuration to clipboard
fastmcp install mcp-json server.py --copy

MCP JSON Generation

The mcp-json subcommand generates standard MCP JSON configuration that can be used with any MCP-compatible client. This is useful when:

Working with MCP clients not directly supported by FastMCP
Creating configuration for CI/CD environments
Sharing server configurations with others
Integration with custom tooling

The generated JSON follows the standard MCP server configuration format used by Claude Desktop, VS Code, Cursor, and other MCP clients, with the server name as the root key:

{
  "server-name": {
    "command": "uv",
    "args": [
      "run",
      "--with",
      "fastmcp",
      "fastmcp",
      "run",
      "/path/to/server.py"
    ],
    "env": {
      "API_KEY": "value"
    }
  }
}

To use this configuration with your MCP client, you’ll typically need to add it to the client’s mcpServers object. Consult your client’s documentation for any specific configuration requirements or formatting needs.

Options specific to mcp-json:

Option	Flag	Description
Copy to Clipboard	`--copy`	Copy configuration to clipboard instead of printing to stdout

`inspect`

New in version: 2.9.0 Generate a detailed JSON report about a FastMCP server, including information about its tools, prompts, resources, and capabilities.

fastmcp inspect server.py

The command supports the same server specification format as run and install:

# Auto-detect server object
fastmcp inspect server.py

# Specify server object
fastmcp inspect server.py:my_server

# Custom output location
fastmcp inspect server.py --output analysis.json

`version`

Display version information about FastMCP and related components.

fastmcp version

Options

Option	Flag	Description
Copy to Clipboard	`--copy`	Copy version information to clipboard

Get Started

Servers

Clients

Integrations

Patterns

Tutorials

Commands Overview

Command Details

`run`

Options

Server Specification

`dev`

Options

`install`

Server Specification

Options

MCP JSON Generation

`inspect`

`version`

Options

Get Started

Servers

Clients

Integrations

Patterns

Tutorials

​Commands Overview

​Command Details

​run

​Options

​Server Specification

​dev

​Options

​install

​Server Specification

​Options

​MCP JSON Generation

​inspect

​version

​Options

Commands Overview

Command Details

`run`

Options

Server Specification

`dev`

Options

`install`

Server Specification

Options

MCP JSON Generation

`inspect`

`version`

Options