This document lists changes made to the Model Context Protocol (MCP) specification since the previous revision, 2025-06-18.

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Major changes

  1. Enhance authorization server discovery with support for OpenID Connect Discovery 1.0. (PR #797)
  2. Allow servers to expose icons as additional metadata for tools, resources and prompts (SEP-973).

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Minor changes

  1. Clarify that servers must respond with HTTP 403 Forbidden for invalid Origin headers in Streamable HTTP transport. (PR #1439)

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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.