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claude-code - 💡(How to fix) Fix [Bug] Claude Opus 4.8: Tool call parsing fails when extended thinking is triggered

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Error Message

(no token output visible) before producing this error

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Bug Description Claude Opus 4.8 frequently fails with "The model's tool call could not be parsed (retry also failed)" whenever extended thinking is triggered.

Repro:

  • Happens on plain conversational turns, not just tool-heavy workflows
  • Triggered whenever the model enters extended/adaptive thinking
  • Reproducible across multiple separate terminal sessions today
  • Same prompts on Opus 4.7 work fine — issue is specific to 4.8

Frequency: very high, most thinking-triggered turns fail

Notes:

  • Opus 4.8 also tends to hang silently in the thinking phase (no token output visible) before producing this error
  • Adaptive thinking can't be disabled via budget_tokens on 4.8, so users have no way to avoid triggering this path
  • Issue #61133 describes the same parse failure on Opus 4.7 (1M); appears to have regressed / re-emerged on 4.8

Environment Info

  • Platform: darwin
  • Terminal: pycharm
  • Version: 2.1.156
  • Feedback ID: 951e763a-7846-4bab-a9e8-3f83b2b77322

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claude-code - 💡(How to fix) Fix [Bug] Claude Opus 4.8: Tool call parsing fails when extended thinking is triggered