Lesson 1: One protocol for every tool: how MCP works
29 min read·13 Oct 2026
Module 4 · Lesson 1 · About 60 minutes · Needs: Module 3, Lesson 1 (tool calling,make_tools,run_tool)
The situation
It is Monday 4 May 2026, week 4. Dev has two requests on his desk. The warranty team wants lookup_order for its own agent, and Priya wants her support chat to check return eligibility. Both mean copying your tools into code you do not own.
Dev would rather serve them once. BrightCart's tools will go behind an MCP server next week, so any agent that speaks the protocol can use them. This lesson builds the first version with two of the eight tools, lookup_order and check_return_eligibility, and traces Aisha's request R-1001 for order 5521 through it.