# Preflight (MCP)

> **TL;DR.** Preflight is a free validator that probes a live MCP server endpoint and checks every requirement — OAuth 2.

- **Category:** AI / Developer Tools / Infrastructure
- **Stage:** validating
- **Age:** 54 days
- **Origin date:** 2026-04-23
- **First detected:** 2026-04-23
- **Canonical URL:** https://earlyterms.com/term/preflight
- **Sources:** 5 primary URLs

## Definition

Preflight is a free validator that probes a live MCP server endpoint and checks every requirement — OAuth 2.1 + PKCE flow, CORS headers, protocol handshake, tool execution, domain verification — before a developer submits to Claude or OpenAI's directories.

M8ven [launched it on April 23, 2026](https://m8ven.ai/preflight) after its founder spent 4 weeks waiting for an OpenAI directory rejection that traced back to a single OAuth redirect bug. The tool runs its full check suite in 15 seconds and is free with no sign-up required.

## Analogy

Think of it as a pre-submission flight simulator: catch the crash in the hangar, not the runway.

## Why it's emerging now

MCP became a multi-vendor standard in 2025; both Claude and OpenAI now run directory review processes that can take 2-4 weeks and reject for trivial OAuth/CORS bugs. The friction of that rejection loop is the market Preflight targets — and it launched the same day this term was first indexed.

## Related terms

- *parent:* Model Context Protocol
- *parent:* MCP Server
- *related:* mcp-server
- *parent:* model-context-protocol
- *related:* MCP Tool
- *related:* mcp-tool
- *related:* OpenAI Agents SDK
- *related:* Claude Agent SDK
- *competitor:* MCP Inspector
- *related:* MCPs
- *related:* OAuth 2.1
- *related:* agent-harness

## Sources

1. [Show HN: Preflight – Test your MCP server before submitting to Claude/OpenAI](https://news.ycombinator.com/item?id=47871631)
2. [M8ven — Preflight MCP server validator](https://m8ven.ai/preflight)
3. [M8ven — trust infrastructure for the agent economy](https://m8ven.ai)
4. [OpenAI — Submit and maintain your app (Apps SDK)](https://developers.openai.com/apps-sdk/deploy/submission)
5. [modelcontextprotocol/inspector — official MCP testing tool on GitHub](https://github.com/modelcontextprotocol/inspector)

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_Generated by EarlyTerms · https://earlyterms.com/term/preflight_