Beta SDKs for the 2026-07-28 MCP Spec Release Candidate Are Here
Model Context Protocol (MCP) has released beta SDKs aligned with the 2026-07-28 spec release candidate. The update introduces key improvements including a new data format and more flexible client-to-server argument passing. Developers are encouraged to test the betas and provide feedback before the final release.
Background
- MCP (Model Context Protocol) is an open standard developed by Anthropic that lets AI models interact with external tools and data sources in a structured way. It's the framework behind "function calling" in Anthropic's Claude models.
- The 2026-07-28 spec release candidate introduces upcoming changes to how these interactions work — these beta SDKs give developers a preview to test with before the final spec ships.
- This matters because MCP is competing with OpenAI's function-calling API and Google's Vertex AI agent protocols. Which standard gains traction affects how all AI assistants will access real-time data and perform actions on users' behalf.
- SDKs (Software Development Kits) are the libraries developers use to implement the protocol in their own applications. The betas let the community test new features and report bugs before the stable release.