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Installation

docs/getting-started/installation.mdx

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Install FastMCP

We recommend using uv to install and manage FastMCP.

bash
pip install fastmcp

Or with uv:

bash
uv add fastmcp

Optional Dependencies

FastMCP provides optional extras for specific features. For example, to install the background tasks extra:

bash
pip install "fastmcp[tasks]"

See Background Tasks for details on the task system.

Verify Installation

To verify that FastMCP is installed correctly, you can run the following command:

bash
fastmcp version

You should see output like the following:

bash
$ fastmcp version

FastMCP version:                           3.0.0
MCP version:                               1.25.0
Python version:                            3.12.2
Platform:            macOS-15.3.1-arm64-arm-64bit
FastMCP root path:            ~/Developer/fastmcp

Dependency Licensing

<Info> FastMCP depends on Cyclopts for CLI functionality. Cyclopts v4 includes docutils as a transitive dependency, which has complex licensing that may trigger compliance reviews in some organizations.

If this is a concern, you can install Cyclopts v5 alpha which removes this dependency:

bash
pip install "cyclopts>=5.0.0a1"

Alternatively, wait for the stable v5 release. See this issue for details. </Info>

Upgrading

From FastMCP 2.0

See the Upgrade Guide for a complete list of breaking changes and migration steps.

From the MCP SDK

From FastMCP 1.0

If you're using FastMCP 1.0 via the mcp package (meaning you import FastMCP as from mcp.server.fastmcp import FastMCP), upgrading is straightforward — for most servers, it's a single import change. See the full upgrade guide for details.

From the Low-Level Server API

If you built your server directly on the mcp package's Server class — with list_tools()/call_tool() handlers and hand-written JSON Schema — see the migration guide for a full walkthrough.

Troubleshooting

import fastmcp fails after a pip upgrade

This affects one specific case: upgrading to FastMCP 3.3 or later from FastMCP 3.2 or earlier with pip. Fresh installs and uv upgrades are unaffected, so you can skip this unless you did exactly that.

If import fastmcp raises ModuleNotFoundError, or from fastmcp import FastMCP raises ImportError, immediately after the upgrade, your install is in a half-removed state. Reinstall in a single step:

bash
pip install --force-reinstall fastmcp

If that doesn't resolve it, remove both distributions and reinstall from a clean state:

bash
pip uninstall -y fastmcp fastmcp-slim
pip install fastmcp

FastMCP 3.3 moved the importable code from the fastmcp distribution into fastmcp-slim. During a single-command pip upgrade, pip can install the new files and then delete them while uninstalling the old fastmcp distribution, whose file manifest still lists those paths. uv uninstalls before it installs, so it is unaffected.

Versioning Policy

FastMCP follows semantic versioning with pragmatic adaptations for the rapidly evolving MCP ecosystem. Breaking changes may occur in minor versions (e.g., 2.3.x to 2.4.0) when necessary to stay current with the MCP Protocol.

For production use, always pin to exact versions:

fastmcp==3.0.0  # Good
fastmcp>=3.0.0  # Bad - may install breaking changes

See the full versioning and release policy for details on our public API, deprecation practices, and breaking change philosophy.

Contributing to FastMCP

Interested in contributing to FastMCP? See the Contributing Guide for details on:

  • Setting up your development environment
  • Running tests and pre-commit hooks
  • Submitting issues and pull requests
  • Code standards and review process