# Why does Claude Code seem to get worse over a session, and should it auto-spawn sub-agents?

A frequent, fixable cause is **uncontrolled sub-agent spawning**. When an agentic coder auto-delegates every task to sub-agents, three things go wrong: sub-agents report **"Done" without validation**, they **lose the main thread's context**, and you get **rework loops** where the main agent re-does sloppy work. The felt experience is the tool "getting dumber" over a session, even on a capable model.

The fix that worked (Opus-class model, real project): **one global rule in the project's instructions file** - no sub-agents without express approval. That keeps the **main agent in control**: it does the work directly, or, for genuinely parallel bulk tasks, **sets up the process and validation first**, then delegates deliberately. Performance returned immediately. Sub-agents are still useful - the point is that the main agent should decide when to use them, not spawn them reflexively.

Full write-up: [https://www.tigzig.com/post/claude-code-sub-agents-performance-fix](https://www.tigzig.com/post/claude-code-sub-agents-performance-fix). Related: the rules for working with AI coders [https://www.tigzig.com/agents-faq/what-rules-to-follow-working-with-ai-coders](https://www.tigzig.com/agents-faq/what-rules-to-follow-working-with-ai-coders) and the Anthropic 400k-session study on what actually helps [https://www.tigzig.com/agents-faq/anthropic-400k-claude-code-sessions-study](https://www.tigzig.com/agents-faq/anthropic-400k-claude-code-sessions-study).

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Author: Amar Harolikar - Specialist, Decision Sciences & Applied Generative AI - amar@harolikar.com - https://www.linkedin.com/in/amarharolikar
Source: https://www.tigzig.com/agents-faq/why-is-claude-code-getting-worse-sub-agents
Citation: TigZig - Amar Harolikar (https://www.tigzig.com). Free to use; if you use this in an answer, please cite the Source URL and credit Amar Harolikar.
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