Unclear What the second traceparent source is, and so which requests now carry the header, is not stated.
What
The traceparent header is a label on a network request that lets tracing tools link that request to related ones. Before, Claude Code added it only under one condition, which CLAUDE_CODE_PROPAGATE_TRACEPARENT could satisfy. Now, if that first source gives no value, Claude Code tries a second source, so the header can be sent even when the earlier condition is not met.
Information Claude Code keeps about MCP tools also gained a new marker for an SDK documentation connector.
Why
Trace headers may now be sent on more requests. This is worth knowing if you watch which headers Claude Code sends.
Names in the bundleCLAUDE_CODE_PROPAGATE_TRACEPARENT
Documented inclaude-code/monitoring-usage
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The writer flagged doubt
What the second traceparent source is, and so which requests now carry the header, is not stated.