OPENAI: TREAT GPT-5.5 AS A NEW MODEL FAMILY, NOT A DROP‑IN UPGRADE
OpenAI’s GPT-5.5 requires fresh prompts and tuning rather than a drop-in replacement of existing stacks. OpenAI’s guidance says to start migration with a clean...
OpenAI’s GPT-5.5 requires fresh prompts and tuning rather than a drop-in replacement of existing stacks.
OpenAI’s guidance says to start migration with a clean baseline and then tune reasoning effort, verbosity, tool descriptions, and output format against real examples—don’t carry over legacy prompt baggage. See the summary and links captured here: Simon Willison’s Blogmarks.
They also recommend a simple UX fix for multi-step tool calls: send a short, user-visible status update before tools run to avoid “it looks stuck” moments. That advice and a Codex migration hint (run the openai-docs skill to “migrate this project to gpt-5.5”) are noted in Blogmarks.
Net: plan a real eval pass, re-baseline prompts, and wire in progress pings for long tool chains. Details via Blogmarks.
Prompt stacks tuned for 5.2/5.4 may regress with 5.5; re-baselining affects timelines, eval coverage, and reliability SLAs.
Progress pings before long tool runs can cut perceived latency and support tickets for “frozen” agents.
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Build a fresh minimal 5.5 prompt and A/B it vs your current stack on representative backend/data workflows; track accuracy, tool-call rate, and end-to-end latency.
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Simulate long multi-step tool calls and test streaming plus pre-tool status messages; measure user abandonment and timeout rates.
Legacy codebase integration strategies...
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Dual-run 5.4 vs 5.5 with shadow traffic and feature flags; gate rollout by workflow after passing eval thresholds.
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Re-validate tool schemas and output contracts; adjust parsing, retry/backoff, and rate limits for any change in verbosity or call frequency.
Fresh architecture paradigms...
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Start from a tiny prompt tied to a strict product contract; grow reasoning effort and tool descriptions only with telemetry feedback.
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Design for streaming and lightweight progress updates on long I/O or reasoning from day one.
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