---
author: "Umesh Malik"
canonical: "https://umesh-malik.com/blog/tag/evaluation"
description: "Explore articles tagged with Evaluation by Umesh Malik — AI Engineer, LLM & GenAI Developer. Learn Evaluation best practices, practical tips, and in-depth guides."
title: "Umesh Malik's Blog - Evaluation Articles | Evaluation Tutorials"
tokens: 167
generator: "scripts/generate-page-markdown.mjs"
---

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# Evaluation

1 article

 [![Swapping bespoke search tools for generic grep, glob and view raised Copilot code review cost until the system prompt was rewritten to be diff-anchored](https://umesh-malik.com/blog/cut-agent-tool-call-cost-prompt-rewrite-cover.png)

AI Coding Agents & DX • Aug 14, 2026

### Cut agent tool call cost: GitHub's 20% fix was a prompt rewrite

Agent tool call cost jumped after you gave it better tools? GitHub hit that on Copilot code review and won ~20% back with a prompt rewrite, not new tools.

9 min read

Read more →](https://umesh-malik.com/blog/cut-agent-tool-call-cost-prompt-rewrite)