Preflight lets devs test MCP servers before marketplace submission
Developer mengjiang built Preflight, a free tool that probes live MCP server endpoints for common issues — the same checks Claude and OpenAI run during review — after a rejected submission cost them seven weeks of waiting.
Score breakdown
Developers shipping MCP servers to Claude or OpenAI marketplaces can use Preflight to catch submission-blocking issues in seconds rather than waiting weeks for a rejection.
- 01Built by developer mengjiang after an OAuth redirect bug caused a 4-week rejection wait from OpenAI, plus a 3-week resubmission delay.
- 02The fix for the rejected bug took only one hour, making the 7-week total wait especially frustrating.
- 03Preflight replicates the same checks Claude and OpenAI run during MCP server review, completing them in ~15 seconds.
Developer mengjiang released Preflight, a free MCP server validation tool, after a firsthand experience with the costly submission review cycle on Claude and OpenAI's marketplaces. An OAuth redirect bug led to a rejection from OpenAI after four weeks of review; the fix itself took only an hour, but resubmission required another three-week wait. That seven-week ordeal for a trivial bug motivated the creation of a tool that replicates those same checks locally in about 15 seconds.
Preflight is hosted at m8ven.ai/preflight and works by probing a live endpoint URL — it does not access source code.
Preflight is hosted at m8ven.ai/preflight and works by probing a live endpoint URL — it does not access source code. There is no signup required and the tool is free to use. It is built out of M8ven, which the author describes as a trust layer for the agent economy. The author is actively soliciting feedback on failure modes the tool does not yet catch.
Key facts
- 01Built by developer mengjiang after an OAuth redirect bug caused a 4-week rejection wait from OpenAI, plus a 3-week resubmission delay.
- 02The fix for the rejected bug took only one hour, making the 7-week total wait especially frustrating.
- 03Preflight replicates the same checks Claude and OpenAI run during MCP server review, completing them in ~15 seconds.
- 04Available at m8ven.ai/preflight — paste a URL, receive a report.
- 05Requires no signup and is free to use.
- 06Probes only the live endpoint; does not access or require source code.
- 07Built as part of M8ven, described as a trust layer for the agent economy.
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