T07-L03 · Agents · Level 3 Builder · 17-minute read, plus 3 hours of doing

The agent that promised Friday

A genomics core facility gets about thirty sample requests a week. A staff scientist answers each one: which kit, which preparation protocol, how much material, the price, the turnaround. He has been using an AI agent to draft the replies (T07-L02 · Hand a Task to an Agent, and Check What It Did), and it saves him an hour a day. So his colleague starts using it too, with her own copy of the instructions. Two weeks later a group leader complains: the facility promised his sequencing by Friday. The standard turnaround is ten working days. Her copy had lost the line "never promise a date", and nobody could say which version had written the reply.

In a company it's a purchasing team with an agent that turns each new supplier quote into a draft row for the comparison sheet. It works well for the buyer who set it up. His colleague runs it with broader permissions, "to save the clicking", and the agent tidies the quote folder while it's at it.

You are at Level 3 Builder: colleagues run your agent and act on what it writes. At Level 2 you supervised an agent on a one-off task. This book shows you how to package one so that everyone runs the same version: instructions in a file, permissions the software enforces, a limit on how long it runs, a test set with known answers, and a README. It also asks the question that comes first: does this job need an agent at all?

After this you can

  • Decide from twenty real cases whether a job needs an agent or a fixed workflow.
  • Package an agent as files in a shared folder: instructions, enforced permissions that allow reading and one output folder, a pinned model, and a turn and spend limit.
  • Write a test set of six to ten cases with known answers, including an incomplete request, an out-of-scope request and an instruction hidden in the input, and a script that checks them.
  • Write a README so a colleague can run the agent, rerun the tests after a change and stop it.
  • Say where your agent stops and work with real credentials begins.

Before you start