Claude Code v2.1.161: OTEL, Parallel Tool Fixes, MCP Secrets

Claude Code v2.1.161 ships several practical improvements for developers using AI coding agents: OpenTelemetry resource attributes are now exposed as metric labels, parallel tool calls are truly independent, and MCP commands no longer leak secrets to the terminal.

OTEL Resource Attributes as Labels

If you've configured OTEL_RESOURCE_ATTRIBUTES with custom dimensions like team or repo, those values are now included as labels on metric datapoints. This lets you slice usage metrics by your own taxonomy without custom exporters.

Parallel Tool Calls: Independent Failure Handling

Previously, a failing Bash command in a parallel tool batch would cancel all other calls in the same batch. Now each tool returns its own result independently — a failed tool doesn't affect others.

MCP Secret Redaction

claude mcp list, get, and add commands previously printed secrets to the terminal. v2.1.161 fixes three specific issues:

${VAR} references in MCP config are no longer expanded
Credential headers are redacted
URL secrets (e.g., in connection strings) are redacted

CLI and Agent Improvements

Agents UI: Rows now show done/total before detail when work is fanned out; peek shows the longest-running item
/mcp: Unused claude.ai connectors are collapsed behind a "Show unused connectors" row
Fullscreen clipboard: On Linux, uses wl-copy, xclip, or xsel when available, copying to both clipboard and PRIMARY selection for middle-click paste. The hint now shows the correct key per terminal
/effort dialog, workflow animations, shimmer: Now honor the "Reduce motion" setting
Windows hooks: Fixed /usr/bin/bash script.sh failing with "command not found" or "cannot execute binary file"
--resume picker: Now shows sessions from the current directory even when it isn't a git worktree (e.g., jj workspaces)
/autofix-pr: No longer reports "cannot run on the default branch" inside git worktrees or other repos
/usage-credits: Now points Team/Enterprise admins to the correct organization usage settings instead of triggering a re-login

Background Sessions and Subagent Fixes

Background subagent output no longer corrupts claude -p stdout when using --output-format text or json
Workflow agents with isolation: "worktree" in background sessions can now edit files inside their own worktree
Background sessions from claude agents now use the model from settings.json instead of the daemon's stale environment model
Completed subagents no longer show as running when an error occurs during result finalization

OpenTelemetry and Logging Fixes

user_prompt, api_request, tool_result, and tool_decision log events are no longer silently dropped when emitted before telemetry initialization completes

Performance and Rendering

Terminal rendering performance improved by stabilizing the layout engine's JIT compilation profile
Rendering performance for large file writes is improved
Fixed EADDRINUSE errors from tools binding Unix sockets under $TMPDIR when CLAUDE_CODE_TMPDIR is a deep path