Source note · Model Context Protocol transports compared
On stdio the server MAY write UTF-8 strings to stderr for any logging purpose, and the client MAY capture, forward or ignore that output and SHOULD NOT assume stderr output indicates an error condition.
Checked 2026-09-30
- Vendor
- Model Context Protocol project
- Product
- MCP specification
- Subsystem
- stdio transport
- Deployment
- local-subprocess
- Region
- not restricted
- Release range
- MCP revisions 2025-11-25 and 2026-07-28
- Checked
- 2026-09-30
Sources
- stdio — Model Context Protocol (modelcontextprotocol.io) · tier 1 standards and regulators · stdio page, opening bullet list, stderr bullets
Cite this note
APA
WarmTransfer. (2026, September 30). Model Context Protocol transports compared: source note mcp-transport-differences-stdio-stderr. WarmTransfer. https://warmtransfer.net/knowledge/claims/mcp-transport-differences-stdio-stderr
BibTeX
@misc{warmtransfer-claim-mcp-transport-differences-stdio-stderr,
title = {Model Context Protocol transports compared: source note mcp-transport-differences-stdio-stderr},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/mcp-transport-differences-stdio-stderr},
note = {Source note mcp-transport-differences-stdio-stderr, checked 2026-09-30}
}