Research

# A Claude agent: 42% fewer agent calls, 36% less on the bill

Benchmark / October 1, 2026 / Krishna Bhatnagar

The same test on a Claude Sonnet 4.5 agent, with the bill measured. Fewer calls and less spent on agent tokens, with prompt caching and without it.

Key result: 42% fewer agent calls on a Claude agent. Claude Sonnet 4.5 agent · 21 paired tasks

## Setup

- Benchmark: τ-bench retail, with simulated customers
- Agent model: Claude Sonnet 4.5
- Pairs: 21 paired tasks without prompt caching; 48 pairs with it
- Spend: The measured bill for agent tokens

## The question

Does it hold on a different model, and does the bill follow the calls? We ran a Claude Sonnet 4.5 agent both ways, task by task, and read the bill for its tokens.

## What we found

On 21 paired tasks without prompt caching, agent calls fell 42% and the measured bill for agent tokens fell 36%.

With prompt caching on, over 48 pairs, agent calls fell 38% and spend fell 26%. Both ways, the agent made fewer calls and spent less.

## Limits

- Small samples: 21 pairs, and 48 with prompt caching.
- One domain, with simulated customers. A pilot measures your own traffic.