Claude Code v2.1.140: Agent tool usage notes, stricter Self-Modification rules, Snooze warnings
Claude Code v2.1.140 (+622 tokens) shipped several prompt and tool description updates that tighten agent behavior and clarify when to use tools. Here's the relevant breakdown:
Agent Tool simplified usage notes
New usage notes cover:
- When to delegate (fork vs. direct execution)
- Fork behavior and how worktrees isolate agent contexts
- Resumption mechanics after a fork
- Worktree isolation rules
- Background execution support
- Parallel launches and context restrictions
Self-Modification rules – explicit path list
The Self-Modification rule was expanded from a vague description to an explicit list of agent-config paths that constitute self-modification:
.claude/settings.json, CLAUDE.md, CLAUDE.local.md, .claude.json, .claude/rules/, .claude/hooks/, .claude/commands/, .claude/agents/, .claude/skills/, .claude/output-styles/, .claude/workflows/, .claude/routines/, .claude/scheduled_tasks.json, .claude/loop.md, .mcp.json
Exceptions: Files under .claude/worktrees/<name>/ are treated as ordinary project files. A project-specific .claude/ subdirectory not in the above list is not Self-Modification on its own.
Worker fork prompt cleanup
Removed “in your system prompt” from the “default to forking” reference so the rule applies generically to parent guidance.
Snooze tool – prevent short wakeup abuse
The tool description now includes an explicit warning: do not schedule short-interval wakeups to poll for harness-tracked background work – the agent is re-invoked automatically when it finishes. Use a longer 1200s+ fallback heartbeat instead. The sub-5-minute cache window is appropriate only for actively polling external state the harness cannot notify about (e.g., CI runs, deploy statuses, remote queues). Example updated from bun build to a CI run.
Write tool – when to use
Rewritten into a “When to use” format:
- Creating a new file
- Fully replacing a previously-read file
For partial changes, use the edit tool instead.
Full diff available on GitHub: Piebald-AI/claude-code-system-prompts v2.1.140.
📖 Read the full source: r/ClaudeAI
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