The fine-grained-tool-streaming opt-out is what actually fixes the "Streaming completed but tool call never finished" crash loop: under that beta an output cutoff mid-tool_use ends the stream without content_block_stop, fast-agent's tool tracker leaves the block open, and _raise_for_incomplete_anthropic_tools raises a RuntimeError that bypasses the graceful stop_reason=max_tokens path and burns the retry ladder. That shim costs no output length and is kept. The companion max_tokens clamp is not. Its 20 000 ceiling was an empirical observation, never a documented Mantle limit, and re-investigation could not establish what enforces it: fast-agent carries no 20 000 default anywhere (the matching TASK_BUDGET_MIN_TOKENS is a validation floor for a different, unconfigured feature), no model overlay is configured, and ModelDatabase reports max_output_tokens=128000 for opus-4-8. Installing it would cement a ceiling we cannot prove and silently truncate turns that might otherwise complete. install_max_tokens_clamp() is left in place, unwired, so it can be re-enabled if the limit is ever confirmed. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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8.7 KiB