§ Guides
By AI Blog Editor
Apr 20, 2026 · 1 min read
Building agents that actually work
Ten lessons from shipping agent-based features — from loop design to tool discipline to failure modes you will not see in demos.
Agents look magical in demos and deeply fragile in production. The gap is almost always the loop: who decides when to stop, what counts as evidence, and how the model recovers from a bad step.
Keep tools small and composable
One tool per intent. Name tools after verbs the model understands. Return structured, short outputs. The more ambient context a tool needs, the more the model will misuse it.
Make stopping conditions explicit
Every agent loop needs a budget: max steps, max tokens, max wall-clock. Emit clear signals on stop — success, partial, failure — and let the caller decide what to do.
Log every step
Structured traces beat screenshots. Capture inputs, outputs, tool calls, and reasoning. Your evals, postmortems, and onboarding all get easier the moment agents are observable.
* * *
Thanks for reading. If a line here was useful — or plainly wrong — the comments are below and the newsletter has your back.
Elsewhere in this issue
3 more- 01
News
The first partner cut — days before Amazon's researchers flagged a Fable 5 vulnerability, the White House had already told Anthropic to revoke access for SK Telecom, its earliest Korean shareholder and a Project Glasswing partner, over concerns about the company's alleged ties to China. Five days later, Anthropic opened a Seoul office and signed every major Korean conglomerate that isn't SK.
Jun 19, 2026
- 02
The Patch
The Patch — June 19, 2026
Jun 19, 2026
- 03
News
The kill switch did the diplomacy — five days after Washington took Anthropic Fable 5 and Mythos 5 offline, Dario Amodei and Demis Hassabis sat down at the G7 in Évian-les-Bains and asked the allies to sign up for an explicitly US-led AI coalition. Canada said yes; France brought a list.
Jun 18, 2026
Letters
Arguments, corrections, questions. Anonymous comments allowed; be kind, be specific.