MCP Logging: Deprecated in 2026
MCP's older logging capability is deprecated as of the 2026-07-28 specification. It remains available during the deprecation window, but new implementations should use ordinary observability tools instead.
Recommended replacements
For stdio servers, write operational logs to stderr so you do not corrupt protocol messages on stdout. For structured distributed observability, use OpenTelemetry-compatible tracing and metrics.
Why this is better
Production teams already have log aggregation, traces, metrics, sampling, retention, and alerting infrastructure. Reusing standard observability avoids creating a protocol-specific logging island.
Never log access tokens, raw secrets, or sensitive tool arguments by default.