Gemini skills, not ChatGPT GPTs: 30分 no-code agent guide

The guide's central argument is that beginners should start where the setup cost is lowest. Instructions written for Gemini's Skills are portable — the same text can be pasted into Claude's Projects or Copilot's Agent Builder — so the effort survives a change of tool.

The warning about ChatGPT's custom GPTs is the clearest practical risk. OpenAI's own FAQ states the feature is scheduled to retire on December 11, 2026, and individual accounts can no longer create new ones, so tutorials that still center on GPTs put beginners on a path with a known end date. The guide also notes OpenAI's Agent Builder ends November 30, 2026, and Gemini's Gems move to skills for individual accounts in November 2026.

Beyond tool choice, the guide treats instruction-writing as the real skill: defining a role, numbering the steps, specifying the output format, and telling the AI what to do when information is missing. It recommends fixing three to five test inputs so improvements can be measured, and appending a rule for each recurring failure. The direct benefit is a working agent in about 30 minutes that shortens daily tasks, provided the output is reviewed before use.