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claude-code - 💡(How to fix) Fix [Bug] Anthropic API: Opus 4.7/4.8 Missing Tool Use Block with tool_use Stop Reason

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Bug Description Opus 4.7 AND 4.8 both produce silent stuck-turns: the assistant message has stop_reason="tool_use" but no tool_use block in content (it stops right after a thinking block). Local transcript scan, aggregated at message.id level, denominator = turns with stop_reason==tool_use: opus-4-7 218/3066 = 7.11% (ongoing since 2026-05-23, not converged), opus-4-8 14/105 = 13.33% (2026-05-29), sonnet-4-6 0/2097 = 0.00% on the same machine over the same period. Hang signature is identical across 4.7 and 4.8 (95% thinking-only, 5% thinking+text). The fact it spans 4.7->4.8 while Sonnet 4.6 is completely clean points to a server-side issue in the Opus thinking->tool_use transition, not a client/version/file-structure problem. Related closed issue: #50727 (was reported as 4.7-only).

Environment Info

  • Platform: darwin
  • Terminal: vscode
  • Version: 2.1.156
  • Feedback ID: 9e2f89b6-a60b-473e-bd08-cab968ee9d82

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claude-code - 💡(How to fix) Fix [Bug] Anthropic API: Opus 4.7/4.8 Missing Tool Use Block with tool_use Stop Reason