The Harness: Routing, Tools and Memory
Short answer: An agent needs a harness: a loop where the model asks for a tool — read the inbox, check the calendar, make an image — your code runs it, and the result goes back to the model. Routing, tools and the record of what has happened are all the harness's job.
The loop, in plain words
The model does not touch your inbox itself. It asks for a tool: read the inbox, check the calendar, make an image. Your code runs that tool, and the result goes back to the model, which decides what to say or ask next. That loop is the harness.
Routing is the harness deciding which tool a request goes to. Memory, in the terms the pillar page supports, is the record the loop works from: the conversation's history in the interface, and the results tools have already returned in this loop. When either is handled badly, the agent looks forgetful or confused even if the model is fine.
Email and calendar run through the harness
The harness is what connects email and calendar, so the model can read the inbox and check the calendar as tools. The Freeborn homepage adds contacts to that list: email, calendar and contacts connected for you.
One rule from the pillar page is not optional: a confirm-before-send step, so a draft email does not send without your confirmation. A draft that sends itself is the failure this step exists to prevent.
The trap in ready-made harnesses
The trap is downloading and fine-tuning local harnesses. You learn them, and they need major updates every week, and then you troubleshoot whatever breaks.
Watch also for tool calls the model formats wrong, and login and API keys stored in plain text. Both are harness problems, not model problems, and both are yours to fix if you built it.
The hours, as estimated on the pillar page
The harness and interface together: about 40 to 80 hours the first time, then about 2 to 4 hours a week. These are the pillar page's estimates, not measured data, and they assume you have built software before. If you have not, add time.
Related DIY pages
Back to the pillar: What it takes to do this yourself
Adults only (18+). What it takes to do this yourself · Apply