5 prompts to give your coding agent before you ship a launch

A developer released MarketMirror, an open-source MCP server and plugin that lets coding agents rehearse product launches against simulated buyers before shipping. The tool runs simulated ad tests, pricing surveys, pitch-and-rebuttal drills and website walkthroughs, returning labelled metrics such as a simulated Fitloop study where requiring a card dropped trial starts from 4.1% to 0.2%. It is installable via uvx from PyPI or the official MCP Registry and supports clients including Claude, Codex, Cursor and Gemini.

Your agent writes the landing page, the pricing table and the launch email. Then you ship, and find out from real customers what was wrong. You can make the same agent rehearse the launch first. Install the MarketMirror plugin or MCP server once, then give it prompts like these. Use MarketMirror to test these three ads on young parents and students in India. Put them in Instagram and Facebook feeds and tell me which one people stop at, which one confuses them, and why. You get thumb-stop, click and hide rates per ad and per audience, with the comments people left. Survey 150 simulated buyers on USD 4.99 a month versus USD 2.99, with and without a card for the free trial. Run it three times and show me the range. In one simulated Fitloop study, the card requirement dropped trial starts from 4.1% to 0.2%. Rehearse this pitch and these rebuttals with the simulated buyers. Tell me which objections my rebuttals fix and which they make worse. In the 2,999-person Fitloop run, the rebuttals pushed "no" from 34.8% to 54.2% simulated . Better to learn that here. Send simulated visitors through https://my-site.example https://my-site.example and record where they hesitate, leave or finish signing up. Run the same survey with Claude and Codex writing and playing different thirds of the market, and show me where they disagree. When they disagree, you've found the part of your plan that's least certain. The quickest way, with uv https://docs.astral.sh/uv/ installed, is one entry in your agent's MCP config the package is marketmirror on PyPI and in the official MCP Registry : { "mcpServers": { "market-mirror": { "command": "uvx", "args": "marketmirror" } } } Then ask the agent to run doctor and setup . Or install from a clone: git clone https://github.com/DarkWorldCoder/market-mirror.git cd market-mirror bash install.sh ./mm configure ./mm agent-config --client claude also: codex, cursor, gemini, generic Every result is simulated and labelled so: use it to choose what to test for real. 👉 https://github.com/DarkWorldCoder/market-mirror https://github.com/DarkWorldCoder/market-mirror a ⭐ helps other people find it Written with help from an AI assistant; numbers are from the saved simulated runs in the README.