Europe 2026
Anthropic Workshop: Build Agents That Run for Hours — Ash Prabaker & Andrew Wilson
Overview
This talk explores the evolution of AI agents, focusing on enabling them to run for extended periods, from minutes to hours or even days. It details the challenges of long-running agents, such as context limitations and model judgment, and presents Anthropic's approach to overcoming these through model improvements and harness development. The discussion highlights how co-evolving models and scaffolding have led to more capable and autonomous AI systems.
Who should watch
- AI engineers and builders working on long-running agent tasks.
- Product Managers seeking to understand the capabilities and limitations of current AI agents.
- Developers interested in the evolution of AI models and their practical applications.
- Those facing challenges with agent context windows, planning, and self-evaluation.
Key takeaways
- Extended agent runtimes are achieved through a combination of model advancements and sophisticated harness development.
- Key challenges for long-running agents include finite context windows, context rot, and models' difficulty in judging their own output.
- Anthropic's Agent SDK provides primitives for building agent harnesses, including core loops, tool integration, and permission systems.
- The development of models like Claude Code and subsequent versions has shown significant improvements in coding ability and runtime duration.
- Techniques like the Ralph Loop and adversarial generator-evaluator patterns are employed to enhance agent performance and reliability.
- The harness design evolves alongside model capabilities, adapting to fill gaps and leverage new strengths, rather than becoming obsolete.
- Structured hand-offs, clean contexts, and adversarial evaluation are effective patterns for building robust agents.
- Reading agent traces manually is a crucial, albeit time-consuming, method for debugging and improving agent behavior.
Notable quotes
*The frontier doesn't really shrink, it just moves.*
*It's very easy for me to critique a lovely piece of artwork or a fine meal, much harder for me to actually go ahead and like paint that or cook that meal myself.*
*The lesson isn't necessarily our harness was wrong, but rather it was right for 4.5, the frontier moved, and we ran a simplified version to see how it worked.*
Unofficial community note. Prefer the recording for nuance.