---
title: Client-Only Package
description: Use FastMCP's client without installing the full server framework.
icon: package
---

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

<VersionBadge version="3.3.0" />

FastMCP's full `fastmcp` package includes everything needed to build and run MCP servers, apps, proxies, and clients. If you are only embedding an MCP client in another framework, building your own LLM host, or testing MCP servers, you can install the smaller client-only package instead.

```bash
pip install "fastmcp-slim[client]"
```

The client-only package uses the `fastmcp` import namespace:

```python
from fastmcp import Client

client = Client("https://example.com/mcp")
```

Use `fastmcp-slim[client]` when your code connects to MCP servers but does not define or run FastMCP servers itself. For example, framework authors can depend on `fastmcp-slim[client]` to provide MCP connectivity without requiring users to install the full FastMCP server stack.

## Supported Usage

Client-only installs support remote and subprocess transports:

```python
from fastmcp import Client

# Remote MCP server
http_client = Client("https://example.com/mcp")

# Local MCP server over stdio
stdio_client = Client("my_server.py")
```

Single-server MCP configuration works as well:

```python
from fastmcp import Client

config = {
    "mcpServers": {
        "weather": {
            "url": "https://weather.example.com/mcp"
        }
    }
}

client = Client(config)
```

Optional sampling handlers are available through the same extras as the full package:

```bash
pip install "fastmcp-slim[client,openai]"
pip install "fastmcp-slim[client,anthropic]"
pip install "fastmcp-slim[client,gemini]"
```

## When to Use the Full Package

Install `fastmcp` when you need server-side FastMCP features:

```bash
pip install fastmcp
```

The full package remains the default for most users and continues to support the existing import style:

```python
from fastmcp import Client, FastMCP

server = FastMCP("Example")
client = Client(server)
```

Use the full package for:

- defining or running FastMCP servers
- in-memory clients connected directly to `FastMCP` server objects
- multi-server MCP configurations
- FastMCP apps, proxies, server auth, middleware, and other server-side features

The `fastmcp-slim` package is intentionally narrower: it is for client-only consumers who want FastMCP's MCP client behavior without depending on the full framework.
