mcp-ui is an SDK that implements the MCP Apps standard for delivering interactive user interfaces over the Model Context Protocol.
The tool solves the problem of building rich web interfaces for AI tools by standardizing how UIs are delivered alongside MCP resources and tools. It works by linking tools to their UIs through metadata, allowing hosts to fetch and render interfaces dynamically. The SDK provides server-side packages for creating UI resources in TypeScript, Ruby, and Python, along with a TypeScript client for rendering those UIs in host applications. The MCP Apps pattern connects tools to their UIs via a resourceUri field in metadata, which hosts then use to retrieve and display the interface.
Developers should choose this tool if they are building AI applications that need to expose interactive interfaces through the Model Context Protocol. It suits projects where tools need rich UI presentation beyond text responses, particularly those targeting MCP Apps-compliant hosts. The project notes that its packages are fully compliant with the MCP Apps specification and ready for production use. The tool pioneered the concept of interactive UI over MCP and directly influenced the standardization of the MCP Apps specification itself.
The project maintains active development across multiple language implementations, with server SDKs available in TypeScript, Ruby, and Python alongside the TypeScript client. The codebase is organized around core concepts including the MCP Apps pattern for linking tools to UIs and the underlying UIResource wire format for payload delivery. Documentation includes examples, a walkthrough, and guidance on supported hosts and security considerations.
