Set default protocol version to the latest specification #83
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Currently, MCP has three versions: 2024-11-05, 2025-03-26, and 2025-06-18. - https://modelcontextprotocol.io/specification/2024-11-05/basic/transports (stdio and HTTP with SSE) - https://modelcontextprotocol.io/specification/2025-03-26/basic/transports (stdio and Streamable HTTP) - https://modelcontextprotocol.io/specification/2025-06-18/basic/transports (stdio and Streamable HTTP) The newer specification supports stdio and Streamable HTTP as transport mechanisms. Only the oldest version, 2024-11-05, supports stdin and HTTP with SSE, but that version is now considered legacy. Given the current behavior of the Ruby SDK, it likely makes more sense to set the default protocol version to the latest one, 2025-06-18, rather than the oldest, 2024-11-05. Ideally, the implementation should adjust its behavior based on the version, but this PR is limited to updating the default protocol version only.
atesgoral
approved these changes
Jul 20, 2025
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Motivation and Context
Currently, MCP has three versions: 2024-11-05, 2025-03-26, and 2025-06-18.
The newer specification supports stdio and Streamable HTTP as transport mechanisms. Only the oldest version, 2024-11-05, supports stdin and HTTP with SSE, but that version is now considered legacy.
Given the current behavior of the Ruby SDK, it likely makes more sense to set the default protocol version to the latest one, 2025-06-18, rather than the oldest, 2024-11-05.
How Has This Been Tested?
Existing tests have been updated.
Breaking Changes
None.
Types of changes
Checklist
Additional context
Ideally, the implementation should adjust its behavior based on the version, but this PR is limited to updating the default protocol version only.