Request B benefits substantially more from an explicit multi-phase workflow because it is broad, judgment-intensive, and likely to affect multiple execution paths. Improving error handling requires the agent to identify current failure modes, determine which exceptions should be caught, preserve useful diagnostic information, prevent partial state corruption, and verify that the resulting behavior remains consistent across the module. An analyze → propose → implement → review sequence separates those concerns and creates checkpoints before consequential edits are made.

Request A is comparatively deterministic. The function and target name are already defined, and the task primarily requires locating references, applying the rename, and running tests or static analysis. Anthropic’s Claude Code guidance states that planning is most useful when the approach is uncertain, the work spans multiple files, or the developer is unfamiliar with the affected code. For a small change that can be described as a straightforward diff, direct implementation is usually preferable. ( https://code.claude.com/docs/en/best-practices )

Anthropic also characterizes prompt chaining as appropriate when a task can be divided into fixed stages and additional latency is justified by increased accuracy. Request B fits that pattern because analysis and review materially reduce the risk of introducing swallowed exceptions or inconsistent recovery behavior. ( https://www.anthropic.com/research/building-effective-agents )

Official references/topics: Prompt Chaining; Plan Before Editing; Multi-Phase Coding Workflows; Verification and Review.