HOW WE BUILT LANGCHAIN'S PAID MEDIA AGENT

Summary from the TLDR Founders newsletter

The strongest results come from giving an agent a well-designed workspace with a sandbox, software, business context, and clear operating instructions. The system prompt becomes a map that helps the agent find what it needs without carrying everything in context. Use models for judgment and code for consistency. Agents need to find the right tools, work within clear permissions, and move from analysis to action. This meant proposing campaign changes, routing them through human approval, and verifying that the changes were applied correctly.