I made my SaaS installable by AI agents. Here's what was broken.

Two weeks ago I watched an agent run a full product launch on Waitlister, my waitlist tool. It created the waitlist, generated and published a landing page, signed up a test address, checked the signup was real by fetching the public page unauthenticated, then unpublished and deleted everything it had made. Nobody touched the dashboard. The interesting part isn't that run. It's what I found while getting there, because almost none of it was visible from a browser. Why I bothered My users are pre-launch founders, which is exactly the group now building landing pages by prompting Claude, Cursor, or v0 instead of opening a site builder. "Add a waitlist to my site" is a normal thing to ask an agent to do, and increasingly nobody types my product name at all. The uncomfortable part is when an agent hits a 404 or installs a package that doesn't exist, it doesn't debug. It picks a different tool in the next sentence and never tells the user it switched. You lose without ever seeing a bounce. What I shipped, in order of how much it turned out to matter Full API coverage for the whole job. Not most of it. More below, because this one was worth the other five combined. A skill.md route. One page written for an agent rather than a person: a decision tree (no API key yet, go this way; account key, go that way), both code paths, and a self-check at the end so the agent can confirm it worked. An OpenAPI spec at a fixed URL. Valid 3.0.3 at /openapi.json , all five endpoints, auth, rate limits, error shapes. Endpoint changes update the spec and the SDK types in the same PR or they don't merge. A real npm SDK , plus four aliases under the names an agent is likely to reach for. An MCP server , 14 tools, so agents that speak MCP get typed calls instead of reading my docs. llms.txt and llms-full.txt , an index of the docs in plain text with a short block at the top saying what this product is and where the golden path starts. What was broken Honest list. The file I wrote for agents was