The Codex tool is distinct from the "GPT-5 Codec" model it contains. The specialized model is tuned only for coding and performs poorly on other tasks. For document analysis, summarization, and strategic thinking, product managers should stick with the general-purpose GPT-5 model for best results.
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Generative AI's most immediate impact for product managers isn't just writing user stories. It's consolidating disparate information sources into a single interface, freeing up the cognitive load wasted on context switching and allowing for deeper strategic thinking.
Recognizing there is no single "best" LLM, AlphaSense built a system to test and deploy various models for different tasks. This allows them to optimize for performance and even stylistic preferences, using different models for their buy-side finance clients versus their corporate users.
Simply offering the latest model is no longer a competitive advantage. True value is created in the system built around the model—the system prompts, tools, and overall scaffolding. This 'harness' is what optimizes a model's performance for specific tasks and delivers a superior user experience.
Browser-based ChatGPT cannot execute code or connect to external APIs, limiting its power. The Codex CLI unlocks these agentic capabilities, allowing it to interact with local files, run scripts, and connect to databases, making it a far more powerful tool for real-world tasks.
Instead of prompting a specialized AI tool directly, experts employ a meta-workflow. They first use a general LLM like ChatGPT or Claude to generate a detailed, context-rich 'master prompt' based on a PRD or user story, which they then paste into the specialized tool for superior results.
While generic AIs in tools like Notion are powerful, they struggle to identify the 'source of truth' in an infinite sea of documents. A purpose-built PM tool has a smaller, defined information domain, making it more effective and reliable for specialized tasks.
Codex exposes every command and step, giving engineers granular control. Claude Code abstracts away complexity with a simpler UI, guessing user intent more often. This reflects a fundamental design difference: precision for technical users versus ease-of-use for non-technical ones.
Building a single, all-purpose AI is like hiring one person for every company role. To maximize accuracy and creativity, build multiple custom GPTs, each trained for a specific function like copywriting or operations, and have them collaborate.
Good Star Labs found GPT-5's performance in their Diplomacy game skyrocketed with optimized prompts, moving it from the bottom to the top. This shows a model's inherent capability can be masked or revealed by its prompt, making "best model" a context-dependent title rather than an absolute one.
While new large language models boast superior performance on technical benchmarks, the practical impact on day-to-day PM productivity is hitting a point of diminishing returns. The leap from one version to the next doesn't unlock significantly new capabilities for common PM workflows.
