Purpose
FastMCP is a Python framework for building MCP (Model Context Protocol) servers and clients. MCP is used to connect LLMs to tools and data, and FastMCP is positioned as a complete MCP application framework covering servers, clients, and interactive applications.
Main Capabilities
FastMCP consists of three pillars:
- Servers: Wrap Python functions into MCP-compliant tools, resources, and prompts. Declare a tool with a Python function, and the schema, validation, and documentation are generated automatically.
- Clients: Connect to any server via URL, with transport negotiation, authentication, and protocol lifecycle managed by the framework, providing full protocol support.
- Apps: Provide tools with interactive UIs that render directly in the conversation.
The framework has best practices built in, so developers only need to focus on their own logic.
Usage
Servers start from ordinary Python code. It is recommended to use uv to add FastMCP to a project. For complete installation instructions (including verification and upgrades), see the official Installation Guide. The official documentation also provides guides for upgrading from FastMCP 3, FastMCP 2, MCP SDK v1 or v2, and the low-level SDK v1 or v2.
If using TypeScript, the official documentation provides a corresponding version, FastMCP for TypeScript, built and maintained by the same team, with the installation command being npm install @prefecthq/fastmcp-ts.
Use Cases
FastMCP is suitable for developers who need to build MCP servers or clients and connect LLMs to tools and data. According to the official description, FastMCP 1.0 was merged into the official MCP Python SDK in 2024; the currently independently maintained project reaches a million downloads per day, and about 70% of MCP servers in various languages are powered by some version of FastMCP.
Ecosystem and Extensions
FastMCP handles the MCP application layer. Prefect Horizon is an enterprise-oriented MCP gateway used to scale servers and tools across teams, providing centralized governance, including management of deployment, discovery, security, and usage. The officially described capabilities include: deploying FastMCP servers from GitHub with branch previews and instant rollback; creating a private registry of all MCPs used by the company; protecting access through SSO and tool-level RBAC; obtaining audit logs, observability, and governance; and recomposing approved tools into dedicated endpoints for teams and agents. FastMCP and Horizon are built by the same team at Prefect.
Documentation and Community
Complete documentation is available at gofastmcp.com, including detailed guides, API references, and advanced patterns. The documentation is also available in llms.txt format: llms.txt is equivalent to a sitemap, listing all pages of the documentation; llms-full.txt contains all the documentation, but may exceed an LLM's context window. For community, you can join the Discord server. For the contribution process, see CONTRIBUTING.md and the Contributing Guide; agents should read AGENTS.md.
Limitations
The materials do not provide specific information such as pricing, platform support scope, or performance metrics.
