FastMCP is a Python framework designed for building servers that expose functions, resources, and prompts to AI models using the Model Context Protocol. It simplifies the development process by automatically deriving tool metadata, input schemas, and documentation directly from Python function signatures and type hints. The framework provides a unified container for managing these components, allowing developers to build modular applications that integrate seamlessly with AI assistants.
The project distinguishes itself through its support for interactive, server-defined user interface components that render directly within AI chat environments. It includes a dynamic middleware pipeline for injecting cross-cutting concerns like authentication and telemetry, alongside a protocol-agnostic transport layer that supports stdio, HTTP, and server-sent events. These capabilities allow for the creation of rich, stateful interactions that extend beyond simple text-based tool execution.
The framework covers a broad capability surface, including comprehensive support for authentication, authorization, and secure deployment. It provides tools for managing long-running tasks, background execution, and complex dependency injection, while offering built-in observability through logging, distributed tracing, and performance monitoring. Developers can also leverage built-in CLI scaffolding and hot-reloading to accelerate the development and testing of server-side logic.
FastMCP is distributed as a Python library, with documentation and tooling focused on streamlining the registration and configuration of local server instances for external AI clients.
