Anthropic — an eleven-step form inside Claude.ai admin settings, which means a Team or Enterprise plan; individual plans have no such screen at all. The listing slug is permanent once published. You attest that you personally ran every tool.

OpenAI — submitted as a plugin, with three things Anthropic does not ask for:

a domain verification token served at a fixed well-known path, on the server's host or a parent host
a live scan of your tool metadata
at least five positive and three negative test cases a reviewer can reproduce with your demo account

Both want a public documentation URL, a privacy policy, a support contact and an icon. Both want demo credentials that work without multi-factor — which quietly decides what kind of account you create for the reviewer, and is worth deciding early rather than the day you submit.