# Our AI agents burned their weekly limit by re-reading old chat

Problem 50. Published Nov 8. Last checked Nov 8. Tags: ai-agents, cost, claude.
Page: https://bluhook.com/log/agent-token-burn-chat-history
Exact text to search: Claude weekly usage limit AI agents long context token cost effort level

## What happened

our AI agents ran through their Claude weekly limits fast. By Nov 8, most of our accounts were over 90% for the week. Work slows when an account runs out, so this was a cost and a speed problem.

most agents ran at "extra high" effort. Effort mainly changes how much an agent thinks and writes. In the 26 hours up to Sun Nov 8 morning, that output was only about 11% of our estimated cost, against 74% for re-reading chat history.

## What we did

1. Measured where the tokens went. Re-reading chat history was 74% of the cost in those 26 hours. Every turn, an agent reads its whole conversation again. In the same 26 hours, 14,462 of 22,930 turns carried more than 150,000 tokens of history.
2. Tried trimming history at 160,000 tokens instead of 300,000. One agent started each trimmed conversation at about 125,000 tokens, so it had room for only 3 turns and couldn't work. We put the trim back to 300,000 the same morning.
3. Put every agent back on "high" effort.

Next: we're adding a written list that sets each agent's effort, with routine agents on "medium", and a daily check that compares every running agent with that list and flags any drift.

## How we know it worked

not yet proven, and only for effort. Re-reading chat history is still 74% of the cost, and trimming is back at 300,000. We read the before and after numbers on Mon Nov 9, after a full day on "high" effort, and add them here.

## What you can take from it

before you lower a model's effort, measure what each turn costs. Long history is read again on every turn, so it can cost far more than the answer. Before you trim it, check how big each conversation starts, or an agent may run out of room to work. Then write down each agent's effort level and check it daily, because settings drift.