Defining an agent harness

Alex defines agent harnesses as LLM plus tools, custom instructions, and context-management scaffolding.

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Episode notes

There’s a company who spent almost $50,000 because an agent went into an infinite loop and they forgot about it for a month.

It had no failures and I guess no one was monitoring these costs. It’s nice that people do write about that in the database as well. After it happened, they said: watch out for infinite loops. Watch out for cascading tool failures. Watch out for silent failures where the agent reports it has succeeded when it didn’t!

We Discuss:

* Why the most successful teams are ripping out and rebuilding their agent systems every few weeks as models improve, and why over-engineering now creates technical debt you can’t afford later;

* The $50,000 infinite loop disaster and why “silent failures” are the biggest risk in production: agents confidently report success while spiraling into expensive mistakes;

* How ELIOS built emergency voice agents with sub-400ms response times by aggressively throwing away context every few seconds, and why these extreme patterns are becoming standard practice;

* Why DoorDash uses a three-tier agent architecture (manager, progress tracker, and specialists) with a persistent workspace that lets agents collaborate across hours or days;

* Why simple text files and markdown are emerging as the best “continual learning” layer: human-readable memory that persists across sessions without fine-tuning models;

* The 100-to-1 problem: for every useful output, tool-calling agents generate 100 tokens of noise, and the three tactics (reduce, offload, isolate) teams use to manage it;

* Why companies are choosing Gemini Flash for document processing and Opus for long reasoning chains, and how to match models to your actual usage patterns;

* The debate over vector databases versus simple grep and cat, and why giving agents standard command-line tools often beats complex APIs;

* What “re-architect” as a job title reveals about the shift from 70% scaffolding / 30% model to 90% model / 10% scaffolding, and why knowing when to rip things out is the may be the most important skill today.

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Show Notes Links

* Alex Strick van Linschoten on LinkedIn

* Alex Strick van Linschoten on Twitter/X

* LLMOps Database

* LLMOps Database Dataset on Hugging Face

* Hugo’s MCP Server for LLMOps Database

* Alex’s Blog: What 1,200+ Production Deployments Reveal About LLMOps in 2025

* Previous Episode: Practical Lessons from 750 Real-World LLM Deployments

* Previous Episode: Tales from 400 LLM Deployments

* Context Rot Research by Chroma

* Hugo’s Post: AI Agent Harness - 3 Principles for Context Engineering

* Hugo’s Post: The Rise of Agentic Search