Give Your AI Agent a Mock Server: mockd as an MCP Tool

Here's a scene that plays out a dozen times a day if you use an AI coding agent: you ask it to build something that calls an external API — a payment service, a notification system, an OAuth flow — and it writes beautiful code. Clean types, proper error handling, good structure. Then it stops. It can't actually run any of it, because the API it's calling doesn't exist locally and the agent has no way to spin one up. So you get code that looks right but hasn't been tested against anything. The agent wrote a Stripe integration without ever seeing a Stripe response. It built a webhook handler without ever receiving a webhook. You're the one who has to close that gap, manually, every time. I kept hitting this wall, and it's the reason mockd ships with 18 MCP tools built in. What MCP gives your agent MCP — Model Context Protocol — is the standard that lets AI agents call external tools programmatically. Instead of just reading and writing files, your agent can interact with services, APIs,