Source note · Model Context Protocol transports compared
On stdio, a client that supports both modern (2026-07-28 and later) and legacy initialize-based MCP versions SHOULD probe with server/discover before any other request; a DiscoverResult or a recognized modern JSON-RPC error means the server is modern, while any other error or no response within a reasonable timeout means legacy and the client falls back to initialize, and the fallback MUST NOT be keyed to one specific error code.
Checked 2026-09-30
- Vendor
- Model Context Protocol project
- Product
- MCP specification
- Subsystem
- backward compatibility
- Deployment
- local-subprocess
- Region
- not restricted
- Release range
- MCP revision 2026-07-28
- Checked
- 2026-09-30
Sources
- stdio — Model Context Protocol (modelcontextprotocol.io) · tier 1 standards and regulators · section Backward Compatibility
Cite this note
APA
WarmTransfer. (2026, September 30). Model Context Protocol transports compared: source note mcp-transport-differences-compat-stdio-probe. WarmTransfer. https://warmtransfer.net/knowledge/claims/mcp-transport-differences-compat-stdio-probe
BibTeX
@misc{warmtransfer-claim-mcp-transport-differences-compat-stdio-probe,
title = {Model Context Protocol transports compared: source note mcp-transport-differences-compat-stdio-probe},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/mcp-transport-differences-compat-stdio-probe},
note = {Source note mcp-transport-differences-compat-stdio-probe, checked 2026-09-30}
}