How do you troubleshoot degraded reasoning quality on Claude Sonnet 5 at low effort?

First confirm whether low effort is actually appropriate for the task category involved, since low effort is specifically intended for tasks that don't require deep reasoning - if the observed degradation is on genuinely complex, multistep problems, this may not be a bug to troubleshoot so much as a mismatch between the task's actual difficulty and the effort level chosen for it.

If the task category genuinely fits low effort but quality still seems degraded relative to expectations, test whether raising effort to medium or high resolves the issue on a representative sample of the affected requests, since Anthropic's own guidance frames raising effort as the primary fix for observed shallow reasoning, rather than compensating through prompt engineering alone.

If effort must stay at low specifically for latency reasons even though the task involves real multistep reasoning, add explicit guidance in the prompt describing the task as involving multistep reasoning and instructing the model to think carefully before responding, which is the documented workaround for this specific latency-versus-quality tension.

Distinguish this from a scenario where thinking has been explicitly disabled rather than just set to low effort, since those are different configurations with different implications - confirm which one is actually in play on the affected requests before concluding that effort tuning, rather than the thinking toggle itself, is the relevant lever to adjust.