MCP for Backend Engineers: When to Use It (and When to Skip It)

"If you only have one consumer, MCP is a liability." Subtitle: Real code, real cost, and an honest answer to the question every AI team gets wrong. TL;DR 1 app · 1 team · 1 toolset → use plain tool calling Multiple teams or AI surfaces → use MCP Existing APIs → wrap them in MCP Early-stage / MVP → skip MCP MCP is a scaling decision, not a starting point. Why This Exists A client had a simple ask: "Let our AI assistant use our REST API." Three teams built three integrations. All three were wrong: