This document lists changes made to the Model Context Protocol (MCP) specification since the previous revision, 2025-03-26.

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Major changes

  1. Removed support for JSON-RPC batching (PR #416)
  2. Added support for structured tool output (PR #371)
  3. Classified MCP servers as OAuth Resource Servers, adding protected resource metadata to discover the corresponding Authorization server. (PR #338)
  4. Clarified security considerations and best practices in the authorization spec and in a new security best practices page.
  5. Added support for elicitation, enabling servers to request additional information from users during interactions. (PR #382)

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Other schema changes

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Full changelog

For a complete list of all changes that have been made since the last protocol revision, see GitHub.