Joan Comadran

Field notes

Field notes.

Notes from building software with AI: AI agents, Claude, token costs, Next.js and Supabase.

Engineering | October 21, 2026

MCP vs function calling: which one your AI agent actually needs (2026)

MCP vs function calling, as of October 2026: they aren't rivals. Function calling is how the model asks for a tool; MCP is how tools get shipped between apps. My verdict, a comparison table, the latest spec changes, and the production code that decides it.

Read article

More recent

14 / 15