Yesterday you pressed run. Today we open the part most agencies hide: writing the actual software behind that button. Software development sounds heavy. It is not. You will learn how to have the agent build a small custom tool for one job, instead of paying monthly for a bloated app that does ninety things you never touch.

Start with a plain English spec. Open a file, write what the tool should take in, what it should give back, and the rules in between. Three short paragraphs. Hand that file to Claude Code and ask it to write the code. The spec is the contract, and the model fills it in.

The agent writes the code, runs it, reads its own error, and fixes it, in a loop, in the terminal. You do not type the code. You read what comes back and say where it is wrong in normal words. This is the real move: you direct, the model types, and the loop closes itself.

Now turn that tool into something the agent can reuse forever. Wrap it as an MCP server, a few lines that expose your function by name. From then on any workflow can call your custom tool the same way it calls a famous one. You just added a new hand to the whole system.

Proof, no numbers attached. The pages on our office site are not pasted by hand. They come out of small tools we wrote exactly this way and call from a run. When we needed a thing no app sold, we built it in an afternoon instead of waiting on a vendor.

So pick the one tool you keep wishing existed for your work. Write the three-paragraph spec, let the agent build it, wrap it as a server. You own it, it costs nothing monthly, and it does your job, not a generic one. The full build is on office dot temerarii dot xyz.

That closes chapter six. You wrote a spec, let the agent build the tool, and wrapped it as a server you own.

Next chapter, we wire that tool into a run so one click calls it, the same way The Big T-M does it.