Every AI platform supports MCP tools. But what happens when the tool you need doesn't exist yet? Maybe you're working with an internal API, a niche SaaS, or a service that nobody has wrapped in MCP. Until now, you'd write a custom server.
Most APIs weren't built for AI agents. Stripe has 300+ endpoints. GitHub's API returns paginated results that change between requests. Slack rate-limits you after 20 calls per minute. None of them were designed for Claude to use directly.
We wrapped dozens of REST APIs into MCP tools and learned that a thin wrapper doesn't work. You need to rethink the interface completely—actions instead of CRUD, consolidated search instead of endless list endpoints, and server-side resilience for pagination and rate limits.
Here's what actually works.
We wrapped Stripe, GitHub, and Slack APIs into MCP tools. Here's what we learned about making REST APIs agent-friendly—what works and what doesn't.