CLAUDE_CODE_OTEL_DIAG_STDERR

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_OTEL_DIAG_STDERR is a Claude Code environment variable. Added between v2.1.143 and v2.1.212 and still present in v2.1.294. It is listed in the official reference.

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_OTEL_DIAG_STDERR=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_OTEL_DIAG_STDERR": "<value>"
  }
}

Related variables

• CLAUDE_CODE_ENABLE_FEEDBACK_SURVEY_FOR_OTEL: Re-enables the session quality survey for enterprise deployments with OTEL enabled.
• CLAUDE_CODE_OTEL_CONTENT_MAX_LENGTH: Caps the length of content attributes on OpenTelemetry spans and logs; the truncation function takes the minimum of this value (default 60 KB) and the standard OTEL attribute-length limits, appending a "[TRUNCATED — Content exceeds NKB limit]" marker.
• CLAUDE_CODE_OTEL_FLUSH_TIMEOUT_MS: OpenTelemetry flush timeout; default 5000ms.
• CLAUDE_CODE_OTEL_HEADERS_HELPER_DEBOUNCE_MS: Debounce for OTEL headers helper.
• CLAUDE_CODE_OTEL_SHUTDOWN_TIMEOUT_MS: OpenTelemetry shutdown timeout; default 2000ms.
• OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT
• OTEL_LOG_ASSISTANT_RESPONSES
• OTEL_LOG_MANAGED_SETTINGS

Frequently asked questions

All variables, searchable: Claude Code environment variables.