Building a Disposable Notion Agent on Cheap Models

TL;DR: We built a one-shot HTTP worker that talks to Notion through MCP. Version one worked. Version two got cheaper and more readable, then failed in a new way. The harness was fine. The tool surface, the model, and the prompt were not the same problem, and we kept treating them as one. We keep seeing the same pitch: put an agent in the cloud, give it tools, let it live in Slack, let it remember you. That is a product. It is not the product we needed. We needed something dumber and more useful. Another service should be able to say "read this Notion page, write a summary somewhere, stop." No chat history. No personality that accretes over weeks. No always-on process. If nobody is calling it, it should cost nothing. We started calling that shape a one-shot agent . One HTTP request. Tools for that request. A JSON result. Then the instance can go away. This is the path we actually walked: first working version, what it got wrong, the Markdown fork, and the cheaper tricks that mattered more than swapping frameworks. The job was never "build a chatbot" The first real task was almost boring. Once a week, pull a skill write-up from Notion, extract what mattered, and append it to a digest page. Callers would name pages in English. They would not paste Notion ids. If a name was ambiguous, the agent should refuse to write rather than guess. If that loop is wrong, people stop trusting write-back. If it is expensive, nobody schedules it. If it needs a human to babysit a terminal, it is not a system. So the constraints were social as much as technical: An external caller owns the schedule. The agent does not. The agent must be allowed to use tools, not just talk about them. Secrets stay in the environment, never in the request body. Idle time should be free. Question you will probably ask: why not a cron script that hits the Notion API directly? Because the task changes every call. This week it is a weekly digest. Next week it is "list in-progress rows and do not write." We did