The Command+K blog
Field notes on AI-native SaaS.
How to ship MCP servers, embed in-product AI assistants, and monetize AI usage — written by the team building the platform.
- MCP education
How does AI function calling and tool execution work?
The model never executes anything: it emits JSON, your code runs the tool, and you append the result and call the model again. The full loop in 20 lines, plus the five failure modes that only show up in production.
Sep 28, 2026 · 8 min - MCP education
MCP vs function calling: what's actually different
MCP and function calling solve different problems. Function calling is a per-model capability; MCP is the cross-model protocol that makes your tools portable. Here's how they fit together in production.
Jun 22, 2026 · 5 min