Source note · Model Context Protocol transports compared
The MCP-Protocol-Version HTTP header was not defined by protocol versions earlier than 2025-06-18; under revision 2026-07-28 a server that supports such clients MAY treat a request omitting the header as protocol version 2025-03-26, and a server that does not support them MUST reject the request.
Checked 2026-09-30
- Vendor
- Model Context Protocol project
- Product
- MCP specification
- Subsystem
- request metadata
- Deployment
- remote-http
- Region
- not restricted
- Release range
- MCP revision 2026-07-28
- Checked
- 2026-09-30
Sources
- Model Context Protocol specification 2026-07-28, Streamable HTTP — Model Context Protocol project · tier 1 standards and regulators · section Request Metadata, subsection Protocol Version Header, final paragraph
Cite this note
APA
WarmTransfer. (2026, September 30). Model Context Protocol transports compared: source note mcp-transport-differences-version-header-origin. WarmTransfer. https://warmtransfer.net/knowledge/claims/mcp-transport-differences-version-header-origin
BibTeX
@misc{warmtransfer-claim-mcp-transport-differences-version-header-origin,
title = {Model Context Protocol transports compared: source note mcp-transport-differences-version-header-origin},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/mcp-transport-differences-version-header-origin},
note = {Source note mcp-transport-differences-version-header-origin, checked 2026-09-30}
}