In the Microsoft 365 Copilot app there is a list called Agents, and under it a New Agent option. An employee selects it, types what the thing should do, and presses Send. Copilot writes the agent's name, its description and its instructions out of that sentence, and rewrites them as the description gets more precise. Microsoft's own support page walks through the steps, and none of them involves code.
Microsoft draws a line between two kinds of agent: Agent Builder is for one person or a small team, while anything meant for a whole department, or needing multi-step work and connections to outside systems, belongs in Copilot Studio. The example Microsoft publishes is an agent that answers questions from a team's SharePoint files and emails.
Take the invoice folder somebody in accounts opens every morning. An agent pointed at that folder can read what is in it, check each document against the rules it was given, and draft the reply, and with the code interpreter capability turned on it can do the arithmetic too. Somebody still looks at the invoice the agent could not match.
Which files an agent may read follows from which files its builder may read, and Microsoft notes that the knowledge sources on offer differ by the user's licence. Ten employees building ten agents produces ten sets of instructions and ten reading lists, each one shaped by whoever was in a hurry that week.
Agent Builder comes inside the Microsoft 365 Copilot licence a company is already paying for.