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Pawel Jozefiak
Pawel Jozefiak

Posted on • Originally published at thoughts.jock.pl

Why I Switched My AI Agent from Opus to Haiku (And It Got Better)

Running an AI agent on Claude Max costs $200 a month. I was hitting weekly usage limits by Friday at 70-80% capacity and almost switched platforms entirely.

Instead, I discovered something counterintuitive: using the right model for each specific task.

My agent: Wiz

Wiz operates with persistent memory and full infrastructure access. It functions more like a junior developer than a chatbot. Hourly task checks, autonomous night shifts, Discord processing, daily reports, job scraping, blog pipeline, production deployments.

Initial approach: Sonnet 4.5 as default, Opus for complex decisions, Haiku for simple lookups. Then automations scaled. Token usage came back.

So I tried something unconventional: making Haiku the baseline.

Why it worked

Most agent work is execution, not creativity:

  • Reading files and running scripts
  • Sending messages and updating task lists
  • Scraping with predefined criteria
  • Generating structured reports
  • Following checklists
  • Triggering automations based on conditions

Haiku excels at precision-based execution. You do not need sophisticated reasoning for these.

The three-tier model

  • Haiku (95%) — execution and automation
  • Sonnet (4%) — user-facing interactions, content creation
  • Opus (1%) — complex reasoning, architecture decisions

Result: weekly usage dropped from 70-80% to ~40% of my Claude Max quota.

The expensive model was slowing things down with extra reasoning I did not need.


Originally published on Digital Thoughts — where I write about building AI agents in the real world.

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